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• I just don't get the C++ Pointer/Reference system.

  - by gnm

  I've never had problems with references as in Python (implicit) or PHP (explicit &). In PHP you write $p = &$myvar; and you have $p as a reference pointing to $myVar. So I know in C++ you can do this: void setToSomething( int& var ) { var = 123; } int myInt; setToSomething( myInt ); Myint is now 123, why? Doesn't & mean "memory address of" x in C++? What do I do then if var is only the adress to myInt and not a pointer? void setToSomething( int* var ) { var* = 123; } int myInt; int* myIntPtr = &myInt; setToSomething( myIntPtr ); Does the above work as expected? I don't understand the difference between * and & in C++ fully. They tell you & is used to get the adress of a variable, but why IN GODS NAME does that help you in functions etc. like in the first example?

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• TypeError: Error #1009: Cannot access a property or method of a null object reference. at RECOVER_fyp1_fla::MainTimeline/abc1()

  - by user2643323

  TypeError: Error #1009: Cannot access a property or method of a null object reference. at RECOVER_fyp1_fla::MainTimeline/abc1() Hi, what does this mean? Can anybody figure it out? Thanks. Code: swatter.addEventListener(Event.ENTER_FRAME,abc1); Mouse.hide(); function abc1(e:Event) { swatter.x = mouseX; swatter.y = mouseY; enter code here mosq1.y = mosq1.y + 2; mosq2.y = mosq2.y + 3; mosq3.y = mosq3.y + 4; mosq4.y = mosq4.y + 5; mosq5.y = mosq5.y + 6; if (mosq1.y > 640) { mosq1.y = -50; } if (mosq2.y > 640) { mosq2.y = -50; } if (mosq3.y > 640) { mosq3.y = -50; } if (mosq4.y > 640) { mosq4.y = -50; } if (mosq5.y > 640) { mosq5.y = -50; } if(swatter.hitTestObject(mosq1)) { //SoundMixer.stopAll(); //three_start_sound1.play(); mosq1.parent.removeChild(mosq1); } if(swatter.hitTestObject(mosq2)) { //SoundMixer.stopAll(); //three_start_sound1.play(); mosq2.parent.removeChild(mosq2); } if(swatter.hitTestObject(mosq3)) { //SoundMixer.stopAll(); //three_start_sound1.play(); mosq3.parent.removeChild(mosq3); } if(swatter.hitTestObject(mosq4)) { //SoundMixer.stopAll(); //three_start_sound1.play(); mosq4.parent.removeChild(mosq4); } if(swatter.hitTestObject(mosq5)) { //SoundMixer.stopAll(); //three_start_sound1.play(); mosq5.parent.removeChild(mosq5); } } enter code here

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• Silverlight Recruiting Application Part 5 - Jobs Module / View

  Now we starting getting into a more code-heavy portion of this series, thankfully though this means the groundwork is all set for the most part and after adding the modules we will have a complete application that can be provided with full source. The Jobs module will have two concerns- adding and maintaining jobs that can then be broadcast out to the website. How they are displayed on the site will be handled by our admin system (which will just poll from this common database), so we aren't too concerned with that, but rather with getting the information into the system and allowing the backend administration/HR users to keep things up to date. Since there is a fair bit of information that we want to display, we're going to move editing to a separate view so we can get all that information in an easy-to-use spot. With all the files created for this module, the project looks something like this: And now... on to the code. XAML for the Job Posting View All we really need for the Job Posting View is a RadGridView and a few buttons. This will let us both show off records and perform operations on the records without much hassle. That XAML is going to look something like this: 01.<Grid x:Name="LayoutRoot" 02.Background="White"> 03.<Grid.RowDefinitions> 04.<RowDefinition Height="30" /> 05.<RowDefinition /> 06.</Grid.RowDefinitions> 07.<StackPanel Orientation="Horizontal"> 08.<Button x:Name="xAddRecordButton" 09.Content="Add Job" 10.Width="120" 11.cal:Click.Command="{Binding AddRecord}" 12.telerik:StyleManager.Theme="Windows7" /> 13.<Button x:Name="xEditRecordButton" 14.Content="Edit Job" 15.Width="120" 16.cal:Click.Command="{Binding EditRecord}" 17.telerik:StyleManager.Theme="Windows7" /> 18.</StackPanel> 19.<telerikGrid:RadGridView x:Name="xJobsGrid" 20.Grid.Row="1" 21.IsReadOnly="True" 22.AutoGenerateColumns="False" 23.ColumnWidth="*" 24.RowDetailsVisibilityMode="VisibleWhenSelected" 25.ItemsSource="{Binding MyJobs}" 26.SelectedItem="{Binding SelectedJob, Mode=TwoWay}" 27.command:SelectedItemChangedEventClass.Command="{Binding SelectedItemChanged}"> 28.<telerikGrid:RadGridView.Columns> 29.<telerikGrid:GridViewDataColumn Header="Job Title" 30.DataMemberBinding="{Binding JobTitle}" 31.UniqueName="JobTitle" /> 32.<telerikGrid:GridViewDataColumn Header="Location" 33.DataMemberBinding="{Binding Location}" 34.UniqueName="Location" /> 35.<telerikGrid:GridViewDataColumn Header="Resume Required" 36.DataMemberBinding="{Binding NeedsResume}" 37.UniqueName="NeedsResume" /> 38.<telerikGrid:GridViewDataColumn Header="CV Required" 39.DataMemberBinding="{Binding NeedsCV}" 40.UniqueName="NeedsCV" /> 41.<telerikGrid:GridViewDataColumn Header="Overview Required" 42.DataMemberBinding="{Binding NeedsOverview}" 43.UniqueName="NeedsOverview" /> 44.<telerikGrid:GridViewDataColumn Header="Active" 45.DataMemberBinding="{Binding IsActive}" 46.UniqueName="IsActive" /> 47.</telerikGrid:RadGridView.Columns> 48.</telerikGrid:RadGridView> 49.</Grid> I'll explain what's happening here by line numbers: Lines 11 and 16: Using the same type of click commands as we saw in the Menu module, we tie the button clicks to delegate commands in the viewmodel. Line 25: The source for the jobs will be a collection in the viewmodel. Line 26: We also bind the selected item to a public property from the viewmodel for use in code. Line 27: We've turned the event into a command so we can handle it via code in the viewmodel. So those first three probably make sense to you as far as Silverlight/WPF binding magic is concerned, but for line 27... This actually comes from something I read onDamien Schenkelman's blog back in the day for creating an attached behavior from any event. So, any time you see me using command:Whatever.Command, the backing for it is actually something like this: SelectedItemChangedEventBehavior.cs: 01.public class SelectedItemChangedEventBehavior : CommandBehaviorBase<Telerik.Windows.Controls.DataControl> 02.{ 03.public SelectedItemChangedEventBehavior(DataControl element) 04.: base(element) 05.{ 06.element.SelectionChanged += new EventHandler<SelectionChangeEventArgs>(element_SelectionChanged); 07.} 08.void element_SelectionChanged(object sender, SelectionChangeEventArgs e) 09.{ 10.// We'll only ever allow single selection, so will only need item index 0 11.base.CommandParameter = e.AddedItems[0]; 12.base.ExecuteCommand(); 13.} 14.} SelectedItemChangedEventClass.cs: 01.public class SelectedItemChangedEventClass 02.{ 03.#region The Command Stuff 04.public static ICommand GetCommand(DependencyObject obj) 05.{ 06.return (ICommand)obj.GetValue(CommandProperty); 07.} 08.public static void SetCommand(DependencyObject obj, ICommand value) 09.{ 10.obj.SetValue(CommandProperty, value); 11.} 12.public static readonly DependencyProperty CommandProperty = 13.DependencyProperty.RegisterAttached("Command", typeof(ICommand), 14.typeof(SelectedItemChangedEventClass), new PropertyMetadata(OnSetCommandCallback)); 15.public static void OnSetCommandCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e) 16.{ 17.DataControl element = dependencyObject as DataControl; 18.if (element != null) 19.{ 20.SelectedItemChangedEventBehavior behavior = GetOrCreateBehavior(element); 21.behavior.Command = e.NewValue as ICommand; 22.} 23.} 24.#endregion 25.public static SelectedItemChangedEventBehavior GetOrCreateBehavior(DataControl element) 26.{ 27.SelectedItemChangedEventBehavior behavior = element.GetValue(SelectedItemChangedEventBehaviorProperty) as SelectedItemChangedEventBehavior; 28.if (behavior == null) 29.{ 30.behavior = new SelectedItemChangedEventBehavior(element); 31.element.SetValue(SelectedItemChangedEventBehaviorProperty, behavior); 32.} 33.return behavior; 34.} 35.public static SelectedItemChangedEventBehavior GetSelectedItemChangedEventBehavior(DependencyObject obj) 36.{ 37.return (SelectedItemChangedEventBehavior)obj.GetValue(SelectedItemChangedEventBehaviorProperty); 38.} 39.public static void SetSelectedItemChangedEventBehavior(DependencyObject obj, SelectedItemChangedEventBehavior value) 40.{ 41.obj.SetValue(SelectedItemChangedEventBehaviorProperty, value); 42.} 43.public static readonly DependencyProperty SelectedItemChangedEventBehaviorProperty = 44.DependencyProperty.RegisterAttached("SelectedItemChangedEventBehavior", 45.typeof(SelectedItemChangedEventBehavior), typeof(SelectedItemChangedEventClass), null); 46.} These end up looking very similar from command to command, but in a nutshell you create a command based on any event, determine what the parameter for it will be, then execute. It attaches via XAML and ties to a DelegateCommand in the viewmodel, so you get the full event experience (since some controls get a bit event-rich for added functionality). Simple enough, right? Viewmodel for the Job Posting View The Viewmodel is going to need to handle all events going back and forth, maintaining interactions with the data we are using, and both publishing and subscribing to events. Rather than breaking this into tons of little pieces, I'll give you a nice view of the entire viewmodel and then hit up the important points line-by-line: 001.public class JobPostingViewModel : ViewModelBase 002.{ 003.private readonly IEventAggregator eventAggregator; 004.private readonly IRegionManager regionManager; 005.public DelegateCommand<object> AddRecord { get; set; } 006.public DelegateCommand<object> EditRecord { get; set; } 007.public DelegateCommand<object> SelectedItemChanged { get; set; } 008.public RecruitingContext context; 009.private QueryableCollectionView _myJobs; 010.public QueryableCollectionView MyJobs 011.{ 012.get { return _myJobs; } 013.} 014.private QueryableCollectionView _selectionJobActionHistory; 015.public QueryableCollectionView SelectedJobActionHistory 016.{ 017.get { return _selectionJobActionHistory; } 018.} 019.private JobPosting _selectedJob; 020.public JobPosting SelectedJob 021.{ 022.get { return _selectedJob; } 023.set 024.{ 025.if (value != _selectedJob) 026.{ 027._selectedJob = value; 028.NotifyChanged("SelectedJob"); 029.} 030.} 031.} 032.public SubscriptionToken editToken = new SubscriptionToken(); 033.public SubscriptionToken addToken = new SubscriptionToken(); 034.public JobPostingViewModel(IEventAggregator eventAgg, IRegionManager regionmanager) 035.{ 036.// set Unity items 037.this.eventAggregator = eventAgg; 038.this.regionManager = regionmanager; 039.// load our context 040.context = new RecruitingContext(); 041.this._myJobs = new QueryableCollectionView(context.JobPostings); 042.context.Load(context.GetJobPostingsQuery()); 043.// set command events 044.this.AddRecord = new DelegateCommand<object>(this.AddNewRecord); 045.this.EditRecord = new DelegateCommand<object>(this.EditExistingRecord); 046.this.SelectedItemChanged = new DelegateCommand<object>(this.SelectedRecordChanged); 047.SetSubscriptions(); 048.} 049.#region DelegateCommands from View 050.public void AddNewRecord(object obj) 051.{ 052.this.eventAggregator.GetEvent<AddJobEvent>().Publish(true); 053.} 054.public void EditExistingRecord(object obj) 055.{ 056.if (_selectedJob == null) 057.{ 058.this.eventAggregator.GetEvent<NotifyUserEvent>().Publish("No job selected."); 059.} 060.else 061.{ 062.this._myJobs.EditItem(this._selectedJob); 063.this.eventAggregator.GetEvent<EditJobEvent>().Publish(this._selectedJob); 064.} 065.} 066.public void SelectedRecordChanged(object obj) 067.{ 068.if (obj.GetType() == typeof(ActionHistory)) 069.{ 070.// event bubbles up so we don't catch items from the ActionHistory grid 071.} 072.else 073.{ 074.JobPosting job = obj as JobPosting; 075.GrabHistory(job.PostingID); 076.} 077.} 078.#endregion 079.#region Subscription Declaration and Events 080.public void SetSubscriptions() 081.{ 082.EditJobCompleteEvent editComplete = eventAggregator.GetEvent<EditJobCompleteEvent>(); 083.if (editToken != null) 084.editComplete.Unsubscribe(editToken); 085.editToken = editComplete.Subscribe(this.EditCompleteEventHandler); 086.AddJobCompleteEvent addComplete = eventAggregator.GetEvent<AddJobCompleteEvent>(); 087.if (addToken != null) 088.addComplete.Unsubscribe(addToken); 089.addToken = addComplete.Subscribe(this.AddCompleteEventHandler); 090.} 091.public void EditCompleteEventHandler(bool complete) 092.{ 093.if (complete) 094.{ 095.JobPosting thisJob = _myJobs.CurrentEditItem as JobPosting; 096.this._myJobs.CommitEdit(); 097.this.context.SubmitChanges((s) => 098.{ 099.ActionHistory myAction = new ActionHistory(); 100.myAction.PostingID = thisJob.PostingID; 101.myAction.Description = String.Format("Job '{0}' has been edited by {1}", thisJob.JobTitle, "default user"); 102.myAction.TimeStamp = DateTime.Now; 103.eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 104.} 105., null); 106.} 107.else 108.{ 109.this._myJobs.CancelEdit(); 110.} 111.this.MakeMeActive(this.regionManager, "MainRegion", "JobPostingsView"); 112.} 113.public void AddCompleteEventHandler(JobPosting job) 114.{ 115.if (job == null) 116.{ 117.// do nothing, new job add cancelled 118.} 119.else 120.{ 121.this.context.JobPostings.Add(job); 122.this.context.SubmitChanges((s) => 123.{ 124.ActionHistory myAction = new ActionHistory(); 125.myAction.PostingID = job.PostingID; 126.myAction.Description = String.Format("Job '{0}' has been added by {1}", job.JobTitle, "default user"); 127.myAction.TimeStamp = DateTime.Now; 128.eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 129.} 130., null); 131.} 132.this.MakeMeActive(this.regionManager, "MainRegion", "JobPostingsView"); 133.} 134.#endregion 135.public void GrabHistory(int postID) 136.{ 137.context.ActionHistories.Clear(); 138._selectionJobActionHistory = new QueryableCollectionView(context.ActionHistories); 139.context.Load(context.GetHistoryForJobQuery(postID)); 140.} Taking it from the top, we're injecting an Event Aggregator and Region Manager for use down the road and also have the public DelegateCommands (just like in the Menu module). We also grab a reference to our context, which we'll obviously need for data, then set up a few fields with public properties tied to them. We're also setting subscription tokens, which we have not yet seen but I will get into below. The AddNewRecord (50) and EditExistingRecord (54) methods should speak for themselves for functionality, the one thing of note is we're sending events off to the Event Aggregator which some module, somewhere will take care of. Since these aren't entirely relying on one another, the Jobs View doesn't care if anyone is listening, but it will publish AddJobEvent (52), NotifyUserEvent (58) and EditJobEvent (63)regardless. Don't mind the GrabHistory() method so much, that is just grabbing history items (visibly being created in the SubmitChanges callbacks), and adding them to the database. Every action will trigger a history event, so we'll know who modified what and when, just in case. ;) So where are we at? Well, if we click to Add a job, we publish an event, if we edit a job, we publish an event with the selected record (attained through the magic of binding). Where is this all going though? To the Viewmodel, of course! XAML for the AddEditJobView This is pretty straightforward except for one thing, noted below: 001.<Grid x:Name="LayoutRoot" 002.Background="White"> 003.<Grid x:Name="xEditGrid" 004.Margin="10" 005.validationHelper:ValidationScope.Errors="{Binding Errors}"> 006.<Grid.Background> 007.<LinearGradientBrush EndPoint="0.5,1" 008.StartPoint="0.5,0"> 009.<GradientStop Color="#FFC7C7C7" 010.Offset="0" /> 011.<GradientStop Color="#FFF6F3F3" 012.Offset="1" /> 013.</LinearGradientBrush> 014.</Grid.Background> 015.<Grid.RowDefinitions> 016.<RowDefinition Height="40" /> 017.<RowDefinition Height="40" /> 018.<RowDefinition Height="40" /> 019.<RowDefinition Height="100" /> 020.<RowDefinition Height="100" /> 021.<RowDefinition Height="100" /> 022.<RowDefinition Height="40" /> 023.<RowDefinition Height="40" /> 024.<RowDefinition Height="40" /> 025.</Grid.RowDefinitions> 026.<Grid.ColumnDefinitions> 027.<ColumnDefinition Width="150" /> 028.<ColumnDefinition Width="150" /> 029.<ColumnDefinition Width="300" /> 030.<ColumnDefinition Width="100" /> 031.</Grid.ColumnDefinitions> 032.<!-- Title --> 033.<TextBlock Margin="8" 034.Text="{Binding AddEditString}" 035.TextWrapping="Wrap" 036.Grid.Column="1" 037.Grid.ColumnSpan="2" 038.FontSize="16" /> 039.<!-- Data entry area--> 040. 041.<TextBlock Margin="8,0,0,0" 042.Style="{StaticResource LabelTxb}" 043.Grid.Row="1" 044.Text="Job Title" 045.VerticalAlignment="Center" /> 046.<TextBox x:Name="xJobTitleTB" 047.Margin="0,8" 048.Grid.Column="1" 049.Grid.Row="1" 050.Text="{Binding activeJob.JobTitle, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}" 051.Grid.ColumnSpan="2" /> 052.<TextBlock Margin="8,0,0,0" 053.Grid.Row="2" 054.Text="Location" 055.d:LayoutOverrides="Height" 056.VerticalAlignment="Center" /> 057.<TextBox x:Name="xLocationTB" 058.Margin="0,8" 059.Grid.Column="1" 060.Grid.Row="2" 061.Text="{Binding activeJob.Location, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}" 062.Grid.ColumnSpan="2" /> 063. 064.<TextBlock Margin="8,11,8,0" 065.Grid.Row="3" 066.Text="Description" 067.TextWrapping="Wrap" 068.VerticalAlignment="Top" /> 069. 070.<TextBox x:Name="xDescriptionTB" 071.Height="84" 072.TextWrapping="Wrap" 073.ScrollViewer.VerticalScrollBarVisibility="Auto" 074.Grid.Column="1" 075.Grid.Row="3" 076.Text="{Binding activeJob.Description, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}" 077.Grid.ColumnSpan="2" /> 078.<TextBlock Margin="8,11,8,0" 079.Grid.Row="4" 080.Text="Requirements" 081.TextWrapping="Wrap" 082.VerticalAlignment="Top" /> 083. 084.<TextBox x:Name="xRequirementsTB" 085.Height="84" 086.TextWrapping="Wrap" 087.ScrollViewer.VerticalScrollBarVisibility="Auto" 088.Grid.Column="1" 089.Grid.Row="4" 090.Text="{Binding activeJob.Requirements, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}" 091.Grid.ColumnSpan="2" /> 092.<TextBlock Margin="8,11,8,0" 093.Grid.Row="5" 094.Text="Qualifications" 095.TextWrapping="Wrap" 096.VerticalAlignment="Top" /> 097. 098.<TextBox x:Name="xQualificationsTB" 099.Height="84" 100.TextWrapping="Wrap" 101.ScrollViewer.VerticalScrollBarVisibility="Auto" 102.Grid.Column="1" 103.Grid.Row="5" 104.Text="{Binding activeJob.Qualifications, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}" 105.Grid.ColumnSpan="2" /> 106.<!-- Requirements Checkboxes--> 107. 108.<CheckBox x:Name="xResumeRequiredCB" Margin="8,8,8,15" 109.Content="Resume Required" 110.Grid.Row="6" 111.Grid.ColumnSpan="2" 112.IsChecked="{Binding activeJob.NeedsResume, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}"/> 113. 114.<CheckBox x:Name="xCoverletterRequiredCB" Margin="8,8,8,15" 115.Content="Cover Letter Required" 116.Grid.Column="2" 117.Grid.Row="6" 118.IsChecked="{Binding activeJob.NeedsCV, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}"/> 119. 120.<CheckBox x:Name="xOverviewRequiredCB" Margin="8,8,8,15" 121.Content="Overview Required" 122.Grid.Row="7" 123.Grid.ColumnSpan="2" 124.IsChecked="{Binding activeJob.NeedsOverview, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}"/> 125. 126.<CheckBox x:Name="xJobActiveCB" Margin="8,8,8,15" 127.Content="Job is Active" 128.Grid.Column="2" 129.Grid.Row="7" 130.IsChecked="{Binding activeJob.IsActive, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}"/> 131. 132.<!-- Buttons --> 133. 134.<Button x:Name="xAddEditButton" Margin="8,8,0,10" 135.Content="{Binding AddEditButtonString}" 136.cal:Click.Command="{Binding AddEditCommand}" 137.Grid.Column="2" 138.Grid.Row="8" 139.HorizontalAlignment="Left" 140.Width="125" 141.telerik:StyleManager.Theme="Windows7" /> 142. 143.<Button x:Name="xCancelButton" HorizontalAlignment="Right" 144.Content="Cancel" 145.cal:Click.Command="{Binding CancelCommand}" 146.Margin="0,8,8,10" 147.Width="125" 148.Grid.Column="2" 149.Grid.Row="8" 150.telerik:StyleManager.Theme="Windows7" /> 151.</Grid> 152.</Grid> The 'validationHelper:ValidationScope' line may seem odd. This is a handy little trick for catching current and would-be validation errors when working in this whole setup. This all comes from an approach found on theJoy Of Code blog, although it looks like the story for this will be changing slightly with new advances in SL4/WCF RIA Services, so this section can definitely get an overhaul a little down the road. The code is the fun part of all this, so let us see what's happening under the hood. Viewmodel for the AddEditJobView We are going to see some of the same things happening here, so I'll skip over the repeat info and get right to the good stuff: 001.public class AddEditJobViewModel : ViewModelBase 002.{ 003.private readonly IEventAggregator eventAggregator; 004.private readonly IRegionManager regionManager; 005. 006.public RecruitingContext context; 007. 008.private JobPosting _activeJob; 009.public JobPosting activeJob 010.{ 011.get { return _activeJob; } 012.set 013.{ 014.if (_activeJob != value) 015.{ 016._activeJob = value; 017.NotifyChanged("activeJob"); 018.} 019.} 020.} 021. 022.public bool isNewJob; 023. 024.private string _addEditString; 025.public string AddEditString 026.{ 027.get { return _addEditString; } 028.set 029.{ 030.if (_addEditString != value) 031.{ 032._addEditString = value; 033.NotifyChanged("AddEditString"); 034.} 035.} 036.} 037. 038.private string _addEditButtonString; 039.public string AddEditButtonString 040.{ 041.get { return _addEditButtonString; } 042.set 043.{ 044.if (_addEditButtonString != value) 045.{ 046._addEditButtonString = value; 047.NotifyChanged("AddEditButtonString"); 048.} 049.} 050.} 051. 052.public SubscriptionToken addJobToken = new SubscriptionToken(); 053.public SubscriptionToken editJobToken = new SubscriptionToken(); 054. 055.public DelegateCommand<object> AddEditCommand { get; set; } 056.public DelegateCommand<object> CancelCommand { get; set; } 057. 058.private ObservableCollection<ValidationError> _errors = new ObservableCollection<ValidationError>(); 059.public ObservableCollection<ValidationError> Errors 060.{ 061.get { return _errors; } 062.} 063. 064.private ObservableCollection<ValidationResult> _valResults = new ObservableCollection<ValidationResult>(); 065.public ObservableCollection<ValidationResult> ValResults 066.{ 067.get { return this._valResults; } 068.} 069. 070.public AddEditJobViewModel(IEventAggregator eventAgg, IRegionManager regionmanager) 071.{ 072.// set Unity items 073.this.eventAggregator = eventAgg; 074.this.regionManager = regionmanager; 075. 076.context = new RecruitingContext(); 077. 078.AddEditCommand = new DelegateCommand<object>(this.AddEditJobCommand); 079.CancelCommand = new DelegateCommand<object>(this.CancelAddEditCommand); 080. 081.SetSubscriptions(); 082.} 083. 084.#region Subscription Declaration and Events 085. 086.public void SetSubscriptions() 087.{ 088.AddJobEvent addJob = this.eventAggregator.GetEvent<AddJobEvent>(); 089. 090.if (addJobToken != null) 091.addJob.Unsubscribe(addJobToken); 092. 093.addJobToken = addJob.Subscribe(this.AddJobEventHandler); 094. 095.EditJobEvent editJob = this.eventAggregator.GetEvent<EditJobEvent>(); 096. 097.if (editJobToken != null) 098.editJob.Unsubscribe(editJobToken); 099. 100.editJobToken = editJob.Subscribe(this.EditJobEventHandler); 101.} 102. 103.public void AddJobEventHandler(bool isNew) 104.{ 105.this.activeJob = null; 106.this.activeJob = new JobPosting(); 107.this.activeJob.IsActive = true; // We assume that we want a new job to go up immediately 108.this.isNewJob = true; 109.this.AddEditString = "Add New Job Posting"; 110.this.AddEditButtonString = "Add Job"; 111. 112.MakeMeActive(this.regionManager, "MainRegion", "AddEditJobView"); 113.} 114. 115.public void EditJobEventHandler(JobPosting editJob) 116.{ 117.this.activeJob = null; 118.this.activeJob = editJob; 119.this.isNewJob = false; 120.this.AddEditString = "Edit Job Posting"; 121.this.AddEditButtonString = "Edit Job"; 122. 123.MakeMeActive(this.regionManager, "MainRegion", "AddEditJobView"); 124.} 125. 126.#endregion 127. 128.#region DelegateCommands from View 129. 130.public void AddEditJobCommand(object obj) 131.{ 132.if (this.Errors.Count > 0) 133.{ 134.List<string> errorMessages = new List<string>(); 135. 136.foreach (var valR in this.Errors) 137.{ 138.errorMessages.Add(valR.Exception.Message); 139.} 140. 141.this.eventAggregator.GetEvent<DisplayValidationErrorsEvent>().Publish(errorMessages); 142. 143.} 144.else if (!Validator.TryValidateObject(this.activeJob, new ValidationContext(this.activeJob, null, null), _valResults, true)) 145.{ 146.List<string> errorMessages = new List<string>(); 147. 148.foreach (var valR in this._valResults) 149.{ 150.errorMessages.Add(valR.ErrorMessage); 151.} 152. 153.this._valResults.Clear(); 154. 155.this.eventAggregator.GetEvent<DisplayValidationErrorsEvent>().Publish(errorMessages); 156.} 157.else 158.{ 159.if (this.isNewJob) 160.{ 161.this.eventAggregator.GetEvent<AddJobCompleteEvent>().Publish(this.activeJob); 162.} 163.else 164.{ 165.this.eventAggregator.GetEvent<EditJobCompleteEvent>().Publish(true); 166.} 167.} 168.} 169. 170.public void CancelAddEditCommand(object obj) 171.{ 172.if (this.isNewJob) 173.{ 174.this.eventAggregator.GetEvent<AddJobCompleteEvent>().Publish(null); 175.} 176.else 177.{ 178.this.eventAggregator.GetEvent<EditJobCompleteEvent>().Publish(false); 179.} 180.} 181. 182.#endregion 183.} 184.} We start seeing something new on line 103- the AddJobEventHandler will create a new job and set that to the activeJob item on the ViewModel. When this is all set, the view calls that familiar MakeMeActive method to activate itself. I made a bit of a management call on making views self-activate like this, but I figured it works for one reason. As I create this application, views may not exist that I have in mind, so after a view receives its 'ping' from being subscribed to an event, it prepares whatever it needs to do and then goes active. This way if I don't have 'edit' hooked up, I can click as the day is long on the main view and won't get lost in an empty region. Total personal preference here. :) Everything else should again be pretty straightforward, although I do a bit of validation checking in the AddEditJobCommand, which can either fire off an event back to the main view/viewmodel if everything is a success or sent a list of errors to our notification module, which pops open a RadWindow with the alerts if any exist. As a bonus side note, here's what my WCF RIA Services metadata looks like for handling all of the validation: private JobPostingMetadata() { } [StringLength(2500, ErrorMessage = "Description should be more than one and less than 2500 characters.", MinimumLength = 1)] [Required(ErrorMessage = "Description is required.")] public string Description; [Required(ErrorMessage="Active Status is Required")] public bool IsActive; [StringLength(100, ErrorMessage = "Posting title must be more than 3 but less than 100 characters.", MinimumLength = 3)] [Required(ErrorMessage = "Job Title is required.")] public bool JobTitle; [Required] public string Location; public bool NeedsCV; public bool NeedsOverview; public bool NeedsResume; public int PostingID; [Required(ErrorMessage="Qualifications are required.")] [StringLength(2500, ErrorMessage="Qualifications should be more than one and less than 2500 characters.", MinimumLength=1)] public string Qualifications; [StringLength(2500, ErrorMessage = "Requirements should be more than one and less than 2500 characters.", MinimumLength = 1)] [Required(ErrorMessage="Requirements are required.")] public string Requirements;   The RecruitCB Alternative See all that Xaml I pasted above? Those are now two pieces sitting in the JobsView.xaml file now. The only real difference is that the xEditGrid now sits in the same place as xJobsGrid, with visibility swapping out between the two for a quick switch. I also took out all the cal: and command: command references and replaced Button events with clicks and the Grid selection command replaced with a SelectedItemChanged event. Also, at the bottom of the xEditGrid after the last button, I add a ValidationSummary (with Visibility=Collapsed) to catch any errors that are popping up. Simple as can be, and leads to this being the single code-behind file: 001.public partial class JobsView : UserControl 002.{ 003.public RecruitingContext context; 004.public JobPosting activeJob; 005.public bool isNew; 006.private ObservableCollection<ValidationResult> _valResults = new ObservableCollection<ValidationResult>(); 007.public ObservableCollection<ValidationResult> ValResults 008.{ 009.get { return this._valResults; } 010.} 011.public JobsView() 012.{ 013.InitializeComponent(); 014.this.Loaded += new RoutedEventHandler(JobsView_Loaded); 015.} 016.void JobsView_Loaded(object sender, RoutedEventArgs e) 017.{ 018.context = new RecruitingContext(); 019.xJobsGrid.ItemsSource = context.JobPostings; 020.context.Load(context.GetJobPostingsQuery()); 021.} 022.private void xAddRecordButton_Click(object sender, RoutedEventArgs e) 023.{ 024.activeJob = new JobPosting(); 025.isNew = true; 026.xAddEditTitle.Text = "Add a Job Posting"; 027.xAddEditButton.Content = "Add"; 028.xEditGrid.DataContext = activeJob; 029.HideJobsGrid(); 030.} 031.private void xEditRecordButton_Click(object sender, RoutedEventArgs e) 032.{ 033.activeJob = xJobsGrid.SelectedItem as JobPosting; 034.isNew = false; 035.xAddEditTitle.Text = "Edit a Job Posting"; 036.xAddEditButton.Content = "Edit"; 037.xEditGrid.DataContext = activeJob; 038.HideJobsGrid(); 039.} 040.private void xAddEditButton_Click(object sender, RoutedEventArgs e) 041.{ 042.if (!Validator.TryValidateObject(this.activeJob, new ValidationContext(this.activeJob, null, null), _valResults, true)) 043.{ 044.List<string> errorMessages = new List<string>(); 045.foreach (var valR in this._valResults) 046.{ 047.errorMessages.Add(valR.ErrorMessage); 048.} 049.this._valResults.Clear(); 050.ShowErrors(errorMessages); 051.} 052.else if (xSummary.Errors.Count > 0) 053.{ 054.List<string> errorMessages = new List<string>(); 055.foreach (var err in xSummary.Errors) 056.{ 057.errorMessages.Add(err.Message); 058.} 059.ShowErrors(errorMessages); 060.} 061.else 062.{ 063.if (this.isNew) 064.{ 065.context.JobPostings.Add(activeJob); 066.context.SubmitChanges((s) => 067.{ 068.ActionHistory thisAction = new ActionHistory(); 069.thisAction.PostingID = activeJob.PostingID; 070.thisAction.Description = String.Format("Job '{0}' has been edited by {1}", activeJob.JobTitle, "default user"); 071.thisAction.TimeStamp = DateTime.Now; 072.context.ActionHistories.Add(thisAction); 073.context.SubmitChanges(); 074.}, null); 075.} 076.else 077.{ 078.context.SubmitChanges((s) => 079.{ 080.ActionHistory thisAction = new ActionHistory(); 081.thisAction.PostingID = activeJob.PostingID; 082.thisAction.Description = String.Format("Job '{0}' has been added by {1}", activeJob.JobTitle, "default user"); 083.thisAction.TimeStamp = DateTime.Now; 084.context.ActionHistories.Add(thisAction); 085.context.SubmitChanges(); 086.}, null); 087.} 088.ShowJobsGrid(); 089.} 090.} 091.private void xCancelButton_Click(object sender, RoutedEventArgs e) 092.{ 093.ShowJobsGrid(); 094.} 095.private void ShowJobsGrid() 096.{ 097.xAddEditRecordButtonPanel.Visibility = Visibility.Visible; 098.xEditGrid.Visibility = Visibility.Collapsed; 099.xJobsGrid.Visibility = Visibility.Visible; 100.} 101.private void HideJobsGrid() 102.{ 103.xAddEditRecordButtonPanel.Visibility = Visibility.Collapsed; 104.xJobsGrid.Visibility = Visibility.Collapsed; 105.xEditGrid.Visibility = Visibility.Visible; 106.} 107.private void ShowErrors(List<string> errorList) 108.{ 109.string nm = "Errors received: \n"; 110.foreach (string anerror in errorList) 111.nm += anerror + "\n"; 112.RadWindow.Alert(nm); 113.} 114.} The first 39 lines should be pretty familiar, not doing anything too unorthodox to get this up and running. Once we hit the xAddEditButton_Click on line 40, we're still doing pretty much the same things except instead of checking the ValidationHelper errors, we both run a check on the current activeJob object as well as check the ValidationSummary errors list. Once that is set, we again use the callback of context.SubmitChanges (lines 68 and 78) to create an ActionHistory which we will use to track these items down the line. That's all? Essentially... yes. If you look back through this post, most of the code and adventures we have taken were just to get things working in the MVVM/Prism setup. Since I have the whole 'module' self-contained in a single JobView+code-behind setup, I don't have to worry about things like sending events off into space for someone to pick up, communicating through an Infrastructure project, or even re-inventing events to be used with attached behaviors. Everything just kinda works, and again with much less code. Here's a picture of the MVVM and Code-behind versions on the Jobs and AddEdit views, but since the functionality is the same in both apps you still cannot tell them apart (for two-strike): Looking ahead, the Applicants module is effectively the same thing as the Jobs module, so most of the code is being cut-and-pasted back and forth with minor tweaks here and there. So that one is being taken care of by me behind the scenes. Next time, we get into a new world of fun- the interview scheduling module, which will pull from available jobs and applicants for each interview being scheduled, tying everything together with RadScheduler to the rescue. Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is called MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been cleaned up so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# level syntax sugar. There is no difference to await a async method or a normal method. A method returning Task will be awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } The above code is already cleaned up, but there are still a lot of things. More clean up can be done, and the state machine can be very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> void IAsyncStateMachine.MoveNext() { try { switch (this.State) { // Orginal code is splitted by "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; IAsyncStateMachine this1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this1.MoveNext()); // Callback break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; IAsyncStateMachine this2 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this2.MoveNext()); // Callback break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync_(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; (multiCallMethodAsyncStateMachine as IAsyncStateMachine).MoveNext(); // Original code are in this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clear - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback Since it is about callback, the simplification  can go even further – the entire state machine can be completely purged. Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is literally pretending to wait. In a await expression, a Task object will be return immediately so that caller is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is named MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine, MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been refactored, so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# language level syntax sugar. There is no difference to await a async method or a normal method. As long as a method returns Task, it is awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } Once again, the above state machine code is already refactored, but it still has a lot of things. More clean up can be done if we only keep the core logic, and the state machine can become very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> public void MoveNext() // IAsyncStateMachine member. { try { switch (this.State) { // Original code is split by "await"s into "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; MultiCallMethodAsyncStateMachine that1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => that1.MoveNext()); break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; MultiCallMethodAsyncStateMachine that2 = this; this.currentTaskToAwait.ContinueWith(_ => that2.MoveNext()); break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] public void SetStateMachine(IAsyncStateMachine stateMachine) // IAsyncStateMachine member. { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; multiCallMethodAsyncStateMachine.MoveNext(); // Original code are moved into this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clean - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback If we focus on the point of callback, the simplification  can go even further – the entire state machine can be completely purged, and we can just keep the code inside MoveNext(). Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is not to wait. In a await expression, a Task object will be return immediately so that execution is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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• Ubuntu 12.04 + Eclipse 64 bits key binding error

  - by user110933

  The text is quite extense so, this is just a part of it: !SESSION 2012-11-23 10:15:52.442 ----------------------------------------------- eclipse.buildId=I20120608-1200 java.version=1.7.0_09 java.vendor=Oracle Corporation BootLoader constants: OS=linux, ARCH=x86_64, WS=gtk, NL=en_US Command-line arguments: -os linux -ws gtk -arch x86_64 !ENTRY org.eclipse.jface 2 0 2012-11-23 10:16:06.408 !MESSAGE Keybinding conflicts occurred. They may interfere with normal accelerator operation. !SUBENTRY 1 org.eclipse.jface 2 0 2012-11-23 10:16:06.408 !MESSAGE A conflict occurred for ALT+SHIFT+R: Binding(ALT+SHIFT+R, ParameterizedCommand(Command(oracle.eclipse.tools.common.services.ui.refactor.rename.command,Rename, Rename the selected text., Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), oracle.eclipse.tools.common.services.ui.refactor.internal.ArtifactRefactoringCommandHandler, ,,true),null), org.eclipse.ui.defaultAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,system) Binding(ALT+SHIFT+R, ParameterizedCommand(Command(org.eclipse.jdt.ui.edit.text.java.rename.element,Rename - Refactoring , Rename the selected element, Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), , ,,true),null), org.eclipse.ui.defaultAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,system) !ENTRY org.eclipse.ui.workbench 4 0 2012-11-23 10:16:10.409 !MESSAGE An unexpected exception was thrown. !STACK 0 java.lang.NullPointerException at org.eclipse.ui.internal.WorkbenchWindow.putToolbarLabel(WorkbenchWindow.java:1697) at org.eclipse.ui.internal.menus.MenuAdditionCacheEntry.createToolBarAdditionContribution(MenuAdditionCacheEntry.java:208) at org.eclipse.ui.internal.menus.MenuAdditionCacheEntry.createContributionItems(MenuAdditionCacheEntry.java:177) at org.eclipse.ui.internal.menus.TrimContributionManager.update(TrimContributionManager.java:224) at org.eclipse.ui.internal.WorkbenchWindow.updateLayoutDataForContents(WorkbenchWindow.java:3874) at org.eclipse.ui.internal.WorkbenchWindow.setCoolBarVisible(WorkbenchWindow.java:3675) at org.eclipse.ui.internal.ViewIntroAdapterPart.setBarVisibility(ViewIntroAdapterPart.java:203) at org.eclipse.ui.internal.ViewIntroAdapterPart.dispose(ViewIntroAdapterPart.java:106) at org.eclipse.ui.internal.WorkbenchPartReference.doDisposePart(WorkbenchPartReference.java:737) at org.eclipse.ui.internal.ViewReference.doDisposePart(ViewReference.java:107) at org.eclipse.ui.internal.WorkbenchPartReference.dispose(WorkbenchPartReference.java:684) at org.eclipse.ui.internal.WorkbenchPage.disposePart(WorkbenchPage.java:1801) at org.eclipse.ui.internal.WorkbenchPage.partRemoved(WorkbenchPage.java:1793) at org.eclipse.ui.internal.ViewFactory.releaseView(ViewFactory.java:257) at org.eclipse.ui.internal.Perspective.dispose(Perspective.java:292) at org.eclipse.ui.internal.WorkbenchPage.dispose(WorkbenchPage.java:1872) at org.eclipse.ui.internal.WorkbenchWindow.closeAllPages(WorkbenchWindow.java:894) at org.eclipse.ui.internal.WorkbenchWindow.hardClose(WorkbenchWindow.java:1729) at org.eclipse.ui.internal.WorkbenchWindow.busyClose(WorkbenchWindow.java:730) at org.eclipse.ui.internal.WorkbenchWindow.access$0(WorkbenchWindow.java:715) at org.eclipse.ui.internal.WorkbenchWindow$6.run(WorkbenchWindow.java:867) at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70) at org.eclipse.ui.internal.WorkbenchWindow.close(WorkbenchWindow.java:865) at org.eclipse.jface.window.WindowManager.close(WindowManager.java:109) at org.eclipse.ui.internal.Workbench$18.run(Workbench.java:1114) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.eclipse.ui.internal.Workbench.busyClose(Workbench.java:1111) at org.eclipse.ui.internal.Workbench.access$15(Workbench.java:1040) at org.eclipse.ui.internal.Workbench$25.run(Workbench.java:1284) at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70) at org.eclipse.ui.internal.Workbench.close(Workbench.java:1282) at org.eclipse.ui.internal.Workbench.close(Workbench.java:1254) at org.eclipse.ui.internal.WorkbenchWindow.busyClose(WorkbenchWindow.java:727) at org.eclipse.ui.internal.WorkbenchWindow.access$0(WorkbenchWindow.java:715) at org.eclipse.ui.internal.WorkbenchWindow$6.run(WorkbenchWindow.java:867) at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70) at org.eclipse.ui.internal.WorkbenchWindow.close(WorkbenchWindow.java:865) at org.eclipse.jface.window.Window.handleShellCloseEvent(Window.java:741) at org.eclipse.jface.window.Window$3.shellClosed(Window.java:687) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:98) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1276) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1300) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1285) at org.eclipse.swt.widgets.Shell.closeWidget(Shell.java:617) at org.eclipse.swt.widgets.Shell.gtk_delete_event(Shell.java:1191) at org.eclipse.swt.widgets.Widget.windowProc(Widget.java:1750) at org.eclipse.swt.widgets.Control.windowProc(Control.java:5116) at org.eclipse.swt.widgets.Display.windowProc(Display.java:4369) at org.eclipse.swt.internal.gtk.OS._gtk_main_do_event(Native Method) at org.eclipse.swt.internal.gtk.OS.gtk_main_do_event(OS.java:8295) at org.eclipse.swt.widgets.Display.eventProc(Display.java:1192) at org.eclipse.swt.internal.gtk.OS._g_main_context_iteration(Native Method) at org.eclipse.swt.internal.gtk.OS.g_main_context_iteration(OS.java:2332) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3177) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2701) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2665) at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2499) at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:679) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:668) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:353) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584) at org.eclipse.equinox.launcher.Main.run(Main.java:1438) at org.eclipse.equinox.launcher.Main.main(Main.java:1414) !SESSION 2012-11-23 10:36:07.863 ----------------------------------------------- eclipse.buildId=I20120608-1200 java.version=1.7.0_09 java.vendor=Oracle Corporation BootLoader constants: OS=linux, ARCH=x86_64, WS=gtk, NL=en_US Command-line arguments: -os linux -ws gtk -arch x86_64 !ENTRY org.eclipse.jface 2 0 2012-11-23 10:36:13.181 !MESSAGE Keybinding conflicts occurred. They may interfere with normal accelerator operation. !SUBENTRY 1 org.eclipse.jface 2 0 2012-11-23 10:36:13.181 !MESSAGE A conflict occurred for ALT+SHIFT+R: Binding(ALT+SHIFT+R, ParameterizedCommand(Command(oracle.eclipse.tools.common.services.ui.refactor.rename.command,Rename, Rename the selected text., Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), oracle.eclipse.tools.common.services.ui.refactor.internal.ArtifactRefactoringCommandHandler, ,,true),null), org.eclipse.ui.defaultAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,system) Binding(ALT+SHIFT+R, ParameterizedCommand(Command(org.eclipse.jdt.ui.edit.text.java.rename.element,Rename - Refactoring , Rename the selected element, Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), , ,,true),null), org.eclipse.ui.defaultAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,system) !ENTRY org.eclipse.osgi 2 1 2012-11-23 10:39:04.681 !MESSAGE NLS unused message: CacheManager_CannotLoadNonUrlLocation in: org.eclipse.equinox.internal.p2.repository.messages !SESSION 2012-11-23 15:14:12.933 ----------------------------------------------- eclipse.buildId=I20120608-1200 java.version=1.7.0_09 java.vendor=Oracle Corporation BootLoader constants: OS=linux, ARCH=x86_64, WS=gtk, NL=en_US Command-line arguments: -os linux -ws gtk -arch x86_64 !ENTRY org.eclipse.jface 2 0 2012-11-23 15:14:23.380 !MESSAGE Keybinding conflicts occurred. They may interfere with normal accelerator operation. !SUBENTRY 1 org.eclipse.jface 2 0 2012-11-23 15:14:23.380 !MESSAGE A conflict occurred for ALT+SHIFT+R: Binding(ALT+SHIFT+R, ParameterizedCommand(Command(oracle.eclipse.tools.common.services.ui.refactor.rename.command,Rename, Rename the selected text., Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), oracle.eclipse.tools.common.services.ui.refactor.internal.ArtifactRefactoringCommandHandler, ,,true),null), org.eclipse.ui.defaultAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,system) Binding(ALT+SHIFT+R, ParameterizedCommand(Command(org.eclipse.jdt.ui.edit.text.java.rename.element,Rename - Refactoring , Rename the selected element, Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), , ,,true),null), org.eclipse.ui.defaultAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,system) !ENTRY org.springframework.ide.eclipse.uaa 4 2 2012-11-23 15:14:32.800 !MESSAGE Problems occurred when invoking code from plug-in: "org.springframework.ide.eclipse.uaa". !STACK 0 java.lang.NullPointerException at org.springframework.ide.eclipse.internal.uaa.monitor.CommandUsageMonitor.startMonitoring(CommandUsageMonitor.java:61) at org.springframework.ide.eclipse.uaa.UaaPlugin$1$1.run(UaaPlugin.java:91) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.springframework.ide.eclipse.uaa.UaaPlugin$1.run(UaaPlugin.java:85) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54) !SESSION 2012-11-23 15:15:21.833 ----------------------------------------------- eclipse.buildId=I20120608-1200 java.version=1.7.0_09 java.vendor=Oracle Corporation BootLoader constants: OS=linux, ARCH=x86_64, WS=gtk, NL=en_US Command-line arguments: -os linux -ws gtk -arch x86_64 !ENTRY org.eclipse.jface 2 0 2012-11-23 15:15:27.283 !MESSAGE Keybinding conflicts occurred. They may interfere with normal accelerator operation. !SUBENTRY 1 org.eclipse.jface 2 0 2012-11-23 15:15:27.283 !MESSAGE A conflict occurred for ALT+SHIFT+R: Binding(ALT+SHIFT+R, ParameterizedCommand(Command(oracle.eclipse.tools.common.services.ui.refactor.rename.command,Rename, Rename the selected text., Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), oracle.eclipse.tools.common.services.ui.refactor.internal.ArtifactRefactoringCommandHandler, ,,true),null), org.eclipse.ui.defaultAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,system) Binding(ALT+SHIFT+R, ParameterizedCommand(Command(org.eclipse.jdt.ui.edit.text.java.rename.element,Rename - Refactoring , Rename the selected element, Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), , ,,true),null), org.eclipse.ui.defaultAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,system) !ENTRY org.eclipse.jface 2 0 2012-11-23 15:18:41.265 !MESSAGE Keybinding conflicts occurred. They may interfere with normal accelerator operation. !SUBENTRY 1 org.eclipse.jface 2 0 2012-11-23 15:18:41.265 !MESSAGE A conflict occurred for ALT+SHIFT+E: Binding(ALT+SHIFT+E, ParameterizedCommand(Command(oracle.eclipse.tools.common.services.ui.refactor.rename.command,Rename, Rename the selected text., Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), oracle.eclipse.tools.common.services.ui.refactor.internal.ArtifactRefactoringCommandHandler, ,,true),null), org.eclipse.ui.emacsAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,user) Binding(ALT+SHIFT+E, ParameterizedCommand(Command(org.eclipse.jdt.ui.edit.text.java.rename.element,Rename - Refactoring , Rename the selected element, Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), , ,,true),null), org.eclipse.ui.emacsAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,user) Binding(ALT+SHIFT+E, ParameterizedCommand(Command(org.eclipse.wst.jsdt.ui.edit.text.java.rename.element,Rename - Refactoring , Rename the selected element, Category(org.eclipse.wst.jsdt.ui.category.refactoring,Refactor - JavaScript,JavaScript Refactoring Actions,true), , ,,true),null), org.eclipse.ui.emacsAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,user) !SESSION 2012-11-23 15:18:56.267 ----------------------------------------------- eclipse.buildId=I20120608-1200 java.version=1.7.0_09 java.vendor=Oracle Corporation BootLoader constants: OS=linux, ARCH=x86_64, WS=gtk, NL=en_US Command-line arguments: -os linux -ws gtk -arch x86_64 !ENTRY org.eclipse.jface 2 0 2012-11-23 15:19:01.605 !MESSAGE Keybinding conflicts occurred. They may interfere with normal accelerator operation. !SUBENTRY 1 org.eclipse.jface 2 0 2012-11-23 15:19:01.605 !MESSAGE A conflict occurred for ALT+SHIFT+E: Binding(ALT+SHIFT+E, ParameterizedCommand(Command(org.eclipse.wst.jsdt.ui.edit.text.java.rename.element,Rename - Refactoring , Rename the selected element, Category(org.eclipse.wst.jsdt.ui.category.refactoring,Refactor - JavaScript,JavaScript Refactoring Actions,true), , ,,true),null), org.eclipse.ui.emacsAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,user) Binding(ALT+SHIFT+E, ParameterizedCommand(Command(org.eclipse.jdt.ui.edit.text.java.rename.element,Rename - Refactoring , Rename the selected element, Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), , ,,true),null), org.eclipse.ui.emacsAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,user) Binding(ALT+SHIFT+E, ParameterizedCommand(Command(oracle.eclipse.tools.common.services.ui.refactor.rename.command,Rename, Rename the selected text., Category(org.eclipse.jdt.ui.category.refactoring,Refactor - Java,Java Refactoring Actions,true), oracle.eclipse.tools.common.services.ui.refactor.internal.ArtifactRefactoringCommandHandler, ,,true),null), org.eclipse.ui.emacsAcceleratorConfiguration, org.eclipse.ui.contexts.window,,,user)

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• How to disabled the input,textarea,select using this code..

  - by kumar

  Hello friends I am using this code in my view.. <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<NorthernTrust.ATP.iTool.Core.Business.Entities.Exceptions.PricingMassEditBE>" %> <script type="text/javascript"> $("#PricingEditExceptions").find("input, select,textarea").attr('disabled', 'disabled'); </script> <%var a = Model; %> <fieldset id="PricingEditExceptions"> <div class="fiveper"> <label>FM#: <span><%=(null != a) ? Model.Asset.FundmasterSec : null%></span></label> <label>TNT#:<span><%=(null != a) ? Model.Asset.TNTSecurity: null%></span></label> <label>CUSIP#: <span><%=(null != a) ? Model.Asset.CUSIP :null%></span></label> <label>Asset:<span><%=(null != a) ? Model.Asset.AssetClassCode: null%></span></label> <label>Issue:<span><%=(null != a) ? Model.Asset.IssueType: null%></span></label> <label>COQ:<span><%=(null != a) ? Model.Asset.CodeCountryofQuotationName: null%></span></label> <label>CCY:<span><%=(null != a) ? Model.Asset.CurrencyCode: null%></span></label> <label>&nbsp;</label> </div> <div class="fiveper"> <input id="check1" type="checkbox" name="PMchk" value="<%=Model.ExceptionID%>" /> <label>ID#: <span><%=(null != a) ? Model.ExceptionID : 0%></span></label> <label for="ExceptionStatus"> Status: <span id="gui-stat-<%=Model.ExceptionID %>"> <%=Model.LookupCodes["C_EXCPT_STAT"].FirstOrDefault(model => model.Key.Trim().Equals(Model.ExceptionStatus.Trim())).Value%></span> </label> <label for="ResolutionCode"> Resolution: <span> <%=Html.DropDownListFor(model => model.ResolutionCode, new SelectList(Model.LookupCodes["C_EXCPT_RESL"], "Key", "Value", (null != Model.ResolutionCode) ? Model.ResolutionCode.Trim() : Model.ResolutionCode))%> </span> </label> <label for="ReasonCode"> Reason: <span><%=Html.DropDownListFor(model => model.ReasonCode, new SelectList(Model.LookupCodes["C_EXCPT_RSN"], "Key", "Value", (null != Model.ReasonCode) ? Model.ReasonCode.Trim() : Model.ReasonCode))%></span> </label> <label>Action Taken:<span><%=Html.DropDownListFor(model => model.ActionCode, new SelectList(Model.LookupCodes["C_EXCPT_ACT"], "Key", "Value", (null != Model.ActionCode) ? Model.ActionCode.Trim() : Model.ActionCode))%></span></label> <label>&nbsp;</label> </div> <div class="fiveper"> <label>Follow-Up:<span class="datepicker-container"><input type="text" id="exc-flwup-<%=Model.ExceptionID %>" name="exc-flwup-<%=Model.ExceptionID %>" value="<%=Model.FollowupDate %>" /></span></label> <label>Inqurity #: <span><%=Html.EditorFor(model => model.IOL)%></span> </label> <label>&nbsp;</label> <label>Comment: <span> <%=Html.TextAreaFor(model => model.Comment, new { })%> <%=Html.ValidationMessageFor(model => model.Comment)%> </span> </label> </div> <div id="hide" style="display:none"> <label><span><%=Model.Sequence %></span></label> <label><span><%=Model.AssignedId %></span></label> <span id="gui-stat-<%=Model.ExceptionID%>"> <%=Model.LookupCodes["C_EXCPT_STAT"].FirstOrDefault(model => model.Key.Trim().Equals(Model.ExceptionStatus.Trim())).Value%></span> <span>Last Updated:</span> <%=Model.LastUpdateUser.StartsWith("ATPB") ? "SYSTEM" : Model.LastUpdateUser%><br /> <%=Model.LastUpdated%> <% if (DateTime.Now.Date == Model.LastUpdated.Value .Date ) {%> <%=Math.Round((DateTime.Now - (DateTime)Model.LastUpdated).TotalHours, 0)%> hr<%} %> <p> <%=Html.EditorFor(model => model.SequenceDateTimeAsString)%> <%=Html.EditorFor(model => model.AssignedId)%> <span><%=Html.EditorFor(model => model.Origination)%></span> </p> </div> </fieldset> <script type="text/javascript"> $(document).ready(function() { function validate_excpt(formData, jqForm, options) { var form = jqForm[0]; } // post-submit callback function showResponse(responseText, statusText, xhr, $form) { if (responseText.substring(0, 16) != "System.Exception") { $('#error-msg-<%=Model.ExceptionID %> span:last').html('<strong>Update successful.</strong>'); } else { $('#error-msg-<%=Model.ExceptionID %> span:last').html('<strong>Update failed.</strong> ' + responseText.substring(0, 48)); } $('#error-msg-<%=Model.ExceptionID %>').removeClass('hide'); $('#gui-stat-<%=Model.ExceptionID %>').html(responseText[1]); } $('#exc-<%=Model.ExceptionID %>').ajaxForm({ target: '#error-msg-<%=Model.ExceptionID %>', beforeSubmit: validate_excpt, success: showResponse, dataType: 'json' }).enable(<%=Model.EnableEdit.ToString().ToLower() %>); $("input[id^='exc-flwup-']").datepicker({ duration: 0, buttonImage: '/Content/images/calender.gif', buttonImageOnly: true, showOn:'button', constrainInput: true, showTime: true, stepMinutes: 30, stepHours: 1, altTimeField: '', time24h: true, minDate: 0 }); $("input[id^='exc-flwup-<%=Model.ExceptionID%>']").click(function() { $(this).val(''); }); $('#ui-timepicker-div').bgiframe(); }); </script> Using this code I am disabling the fields when the view loads.. like this my view displyas for number of users which I am going to selct using this below code I am able to disable only first Fiedset not for other fieldsets? $("#Fieldset1").find("input, select,textarea").attr('disabled', 'disabled'); why its happening? I need to disable for how many users I select.... thanks..

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• rand() generating the same number – even with srand(time(NULL)) in my main!

  - by Nick Sweet

  So, I'm trying to create a random vector (think geometry, not an expandable array), and every time I call my random vector function I get the same x value, thought y and z are different. int main () { srand ( (unsigned)time(NULL)); Vector<double> a; a.randvec(); cout << a << endl; return 0; } using the function //random Vector template <class T> void Vector<T>::randvec() { const int min=-10, max=10; int randx, randy, randz; const int bucket_size = RAND_MAX/(max-min); do randx = (rand()/bucket_size)+min; while (randx <= min && randx >= max); x = randx; do randy = (rand()/bucket_size)+min; while (randy <= min && randy >= max); y = randy; do randz = (rand()/bucket_size)+min; while (randz <= min && randz >= max); z = randz; } For some reason, randx will consistently return 8, whereas the other numbers seem to be following the (pseudo) randomness perfectly. However, if I put the call to define, say, randy before randx, randy will always return 8. Why is my first random number always 8? Am I seeding incorrectly?

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• Creating a MiniDump of a running process

  - by Lodle

  Im trying to make a tool for my end users that can create a MiniDump of my application if it hangs (i.e. external to the app). Im using the same code as the internal MiniDumper but with the handle and processid of the app but i keep getting error code 0xD0000024 when calling MiniDumpWriteDump. Any ideas? void produceDump( const char* exe ) { DWORD processId = 0; HANDLE process = findProcess(exe, processId); if (!process || processId == 0) { printf("Unable to find exe %s to produce dump.\n", exe); return; } LONG retval = EXCEPTION_CONTINUE_SEARCH; HWND hParent = NULL; // find a better value for your app // firstly see if dbghelp.dll is around and has the function we need // look next to the EXE first, as the one in System32 might be old // (e.g. Windows 2000) HMODULE hDll = NULL; char szDbgHelpPath[_MAX_PATH]; if (GetModuleFileName( NULL, szDbgHelpPath, _MAX_PATH )) { char *pSlash = _tcsrchr( szDbgHelpPath, '\\' ); if (pSlash) { _tcscpy( pSlash+1, "DBGHELP.DLL" ); hDll = ::LoadLibrary( szDbgHelpPath ); } } if (hDll==NULL) { // load any version we can hDll = ::LoadLibrary( "DBGHELP.DLL" ); } LPCTSTR szResult = NULL; int err = 0; if (hDll) { MINIDUMPWRITEDUMP pDump = (MINIDUMPWRITEDUMP)::GetProcAddress( hDll, "MiniDumpWriteDump" ); if (pDump) { char szDumpPath[_MAX_PATH]; char szScratch [_MAX_PATH]; time_t rawtime; struct tm * timeinfo; time ( &rawtime ); timeinfo = localtime ( &rawtime ); char comAppPath[MAX_PATH]; SHGetFolderPath(NULL, CSIDL_COMMON_APPDATA , NULL, SHGFP_TYPE_CURRENT, comAppPath ); //COMMONAPP_PATH _snprintf(szDumpPath, _MAX_PATH, "%s\\DN", comAppPath); CreateDirectory(szDumpPath, NULL); _snprintf(szDumpPath, _MAX_PATH, "%s\\DN\\D", comAppPath); CreateDirectory(szDumpPath, NULL); _snprintf(szDumpPath, _MAX_PATH, "%s\\DN\\D\\dumps", comAppPath); CreateDirectory(szDumpPath, NULL); char fileName[_MAX_PATH]; _snprintf(fileName, _MAX_PATH, "%s_Dump_%04d%02d%02d_%02d%02d%02d.dmp", exe, timeinfo->tm_year+1900, timeinfo->tm_mon, timeinfo->tm_mday, timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec ); _snprintf(szDumpPath, _MAX_PATH, "%s\\DN\\D\\dumps\\%s", comAppPath, fileName); // create the file HANDLE hFile = ::CreateFile( szDumpPath, GENERIC_WRITE, FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL ); if (hFile!=INVALID_HANDLE_VALUE) { MINIDUMP_CALLBACK_INFORMATION mci; mci.CallbackRoutine = (MINIDUMP_CALLBACK_ROUTINE)MyMiniDumpCallback; mci.CallbackParam = 0; MINIDUMP_TYPE mdt = (MINIDUMP_TYPE)(MiniDumpWithPrivateReadWriteMemory | MiniDumpWithDataSegs | MiniDumpWithHandleData | //MiniDumpWithFullMemoryInfo | //MiniDumpWithThreadInfo | MiniDumpWithProcessThreadData | MiniDumpWithUnloadedModules ); // write the dump BOOL bOK = pDump( process, processId, hFile, mdt, NULL, NULL, &mci ); DWORD lastErr = GetLastError(); if (bOK) { printf("Crash dump saved to: %s\n", szDumpPath); return; } else { _snprintf( szScratch, _MAX_PATH, "Failed to save dump file to '%s' (error %u)", szDumpPath, lastErr); szResult = szScratch; err = ERR_CANTSAVEFILE; } ::CloseHandle(hFile); } else { _snprintf( szScratch, _MAX_PATH, "Failed to create dump file '%s' (error %u)", szDumpPath, GetLastError()); szResult = szScratch; err = ERR_CANTMAKEFILE; } } else { szResult = "DBGHELP.DLL too old"; err = ERR_DBGHELP_TOOLD; } } else { szResult = "DBGHELP.DLL not found"; err = ERR_DBGHELP_NOTFOUND; } printf("Could not produce a crash dump of %s.\n\n[error: %u %s].\n", exe, err, szResult); return; } this code works 100% when its internal to the process (i.e. with SetUnhandledExceptionFilter)

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• Finding the distance between 2 points in Android using Cursor and the distanceTo() method

  - by LordSnoutimus

  Hello, I am trying to calculate the distance between the first GPS point stored in a SQLite database and the last GPs point stored. My code so far is this: private double Distance() { SQLiteDatabase db1 = waypoints.getWritableDatabase(); Cursor cursor = db1.query(TABLE_NAME, FROM, null, null, null, null,ORDER_BY); Cursor cursor1 = db1.query(TABLE_NAME, FROM, null, null, null, null,ORDER_BY); Double lat = cursor.getDouble(2); Double lon = cursor.getDouble(1); cursor.moveToFirst(); cursor.moveToLast(); cursor.close(); distance = cursor.distanceTo(cursor1); } I realise I need to return a value but the error I am receiving is for the distanceTo method "The method distanceTo(Cursor) is undefined for the type Cursor" Thanks.

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• Why this strange behavior of sqlbulkcopy in a asp.net website running under iis?

  - by Pandiya Chendur

  I'm using SqlClient.SqlBulkCopy to try and bulk copy a csv file into a database. I am getting the following error after calling the ..WriteToServer method. "The given value of type String from the data source cannot be converted to type bit of the specified target column." Here is my code, dt.Columns.Add("IsDeleted", typeof(byte)); dt.Columns.Add(new DataColumn("CreatedDate", typeof(DateTime))); foreach (DataRow dr in dt.Rows) { if (dr["MobileNo2"] == "" && dr["DriverName2"] == "") { dr["MobileNo2"] = null; dr["DriverName2"] = ""; } dr["IsDeleted"] = Convert.ToByte(0); dr["CreatedDate"] = Convert.ToDateTime(System.DateTime.Now.ToString()); } string connectionString = System.Configuration.ConfigurationManager. ConnectionStrings["connectionString"].ConnectionString; SqlBulkCopy sbc = new SqlBulkCopy(connectionString); sbc.DestinationTableName = "DailySchedule"; sbc.ColumnMappings.Add("WirelessId", "WirelessId"); sbc.ColumnMappings.Add("RegNo", "RegNo"); sbc.ColumnMappings.Add("DriverName1", "DriverName1"); sbc.ColumnMappings.Add("MobileNo1", "MobileNo1"); sbc.ColumnMappings.Add("DriverName2", "DriverName2"); sbc.ColumnMappings.Add("MobileNo2", "MobileNo2"); sbc.ColumnMappings.Add("IsDeleted", "IsDeleted"); sbc.ColumnMappings.Add("CreatedDate", "CreatedDate"); sbc.WriteToServer(dt); sbc.Close(); There is no error when running under visual studio developement server but it gives me an error when running under iis..... Here is my sql server table details, [Id] [int] IDENTITY(1,1) NOT NULL, [WirelessId] [int] NULL, [RegNo] [nvarchar](50) NULL, [DriverName1] [nvarchar](50) NULL, [MobileNo1] [numeric](18, 0) NULL, [DriverName2] [nvarchar](50) NULL, [MobileNo2] [numeric](18, 0) NULL, [IsDeleted] [tinyint] NULL, [CreatedDate] [datetime] NULL,

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• Wpf Resource: "Unknown Build Error, 'Path cannot be null..."

  - by Femaref

  The following is a snippet from a xaml defining a DataGrid in a Control, defining a template selector. <DataGrid.Resources> <selector:CurrencyColorSelector x:Key="currencyColorSelector"> <selector:CurrencyColorSelector.NegativeTemplate> <DataTemplate> <TextBlock Text="{Binding Balance, StringFormat=n}" Background="Red"/> </DataTemplate> </selector:CurrencyColorSelector.NegativeTemplate> <selector:CurrencyColorSelector.NormalTemplate> <DataTemplate> <TextBlock Text="{Binding Balance, StringFormat=n}"/> </DataTemplate> </selector:CurrencyColorSelector.NormalTemplate> </selector:CurrencyColorSelector> </DataGrid.Resources> Now, an error is thrown: "Unknown build error, 'Path cannot be null. Parameter name: path Line 27 Position 79.'" (Compiler or xaml validation error). I have no idea where this Path comes from, neither does my example show anything of it. If you doubleclick the error, it points to the end of the first line. Did anybody encounter such a problem and has a solution for it? The example was from here: http://www.wpftutorial.net/DataGrid.html (Row Details depending on the type of data)

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• jquery and requirejs and knockout; reference requirejs object from within itself

  - by Thomas

  We use jquery and requirejs to create a 'viewmodel' like this: define('vm.inkoopfactuurAanleveren', ['jquery', 'underscore', 'ko', 'datacontext', 'router', 'messenger', 'config', 'store'], function ($, _, ko, datacontext, router, messenger, config, store) { var isBusy = false, isRefreshing = false, inkoopFactuur = { factuurNummer: ko.observable("AAA") }, activate = function (routeData, callback) { messenger.publish.viewModelActivated({ canleaveCallback: canLeave }); getNewInkoopFactuurAanleveren(callback); var restricteduploader = new qq.FineUploader({ element: $('#restricted-fine-uploader')[0], request: { endpoint: 'api/InkoopFactuurAanleveren', forceMultipart: true }, multiple: false, failedUploadTextDisplay: { mode: 'custom', maxChars: 250, responseProperty: 'error', enableTooltip: true }, text: { uploadButton: 'Click or Drop' }, showMessage: function (message) { $('#restricted-fine-uploader').append('<div class="alert alert-error">' + message + '</div>'); }, debug: true, callbacks: { onComplete: function (id, fileName, responseJSON) { var response = responseJSON; }, } }); }, invokeFunctionIfExists = function (callback) { if (_.isFunction(callback)) { callback(); } }, loaded = function (factuur) { inkoopFactuur = factuur; var ids = config.viewIds; ko.applyBindings(this, getView(ids.inkoopfactuurAanleveren)); /*<----- THIS = OUT OF SCOPE!*/ / }, bind = function () { }, saved = function (success) { var s = success; }, saveCmd = ko.asyncCommand({ execute: function (complete) { $.when(datacontext.saveNewInkoopFactuurAanleveren(inkoopFactuur)) .then(saved).always(complete); return; }, canExecute: function (isExecuting) { return true; } }), getView = function (viewName) { return $(viewName).get(0); }, getNewInkoopFactuurAanleveren = function (callback) { if (!isRefreshing) { isRefreshing = true; $.when(datacontext.getNewInkoopFactuurAanleveren(dataOptions(true))).then(loaded).always(invokeFunctionIfExists(callback)); isRefreshing = false; } }, dataOptions = function (force) { return { results: inkoopFactuur, // filter: sessionFilter, //sortFunction: sort.sessionSort, forceRefresh: force }; }, canLeave = function () { return true; }, forceRefreshCmd = ko.asyncCommand({ execute: function (complete) { //$.when(datacontext.sessions.getSessionsAndAttendance(dataOptions(true))) // .always(complete); complete; } }), init = function () { // activate(); // Bind jQuery delegated events //eventDelegates.sessionsListItem(gotoDetails); //eventDelegates.sessionsFavorite(saveFavorite); // Subscribe to specific changes of observables //addFilterSubscriptions(); }; init(); return { activate: activate, canLeave: canLeave, inkoopFactuur: inkoopFactuur, saveCmd: saveCmd, forceRefreshCmd: forceRefreshCmd, bind: bind, invokeFunctionIfExists: invokeFunctionIfExists }; }); On the line ko.applyBindings(this, getView(ids.inkoopfactuurAanleveren)); in the 'loaded' method the 'this' keyword doens't refer to the 'viewmodel' object. the 'self' keyword seems to refer to a combination on methods found over multiple 'viewmodels'. The saveCmd property is bound through knockout, but gives an error since it cannot be found. How can the ko.applyBindings get the right reference to the viewmodel? In other words, with what do we need to replace the 'this' keyword int he applyBindings. I would imagine you can 'ask' requirejs to give us the ealiers instantiated object with identifier 'vm.inkoopfactuurAanleveren' but I cannot figure out how.

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• Problem with FtpFindFirstFile

  - by Xaver

  I want to download all file from ftp directory i want use for that FtpFindFirstFile and FtpGetFile; LPWIN32_FIND_DATA FileData; TCHAR* APP_NAME = TEXT("ftpcli"); TCHAR* PATH_FTP = TEXT("ftp://127.0.01"); TCHAR* ADR_FTP = TEXT("127.0.0.1"); TCHAR* LC_FILE = TEXT("C:\\!"); TCHAR* PATH_FILE = TEXT("/Soft/DVD_Players/WinDVD6"); UINT a; HINTERNET opn; HINTERNET conn; a = InternetAttemptConnect(0); if (a == ERROR_SUCCESS ) { if(InternetCheckConnection(PATH_FTP,FLAG_ICC_FORCE_CONNECTION, NULL)) { opn = InternetOpen(APP_NAME, INTERNET_OPEN_TYPE_DIRECT, NULL, NULL, INTERNET_FLAG_ASYNC); conn = InternetConnect(opn, ADR_FTP, INTERNET_DEFAULT_FTP_PORT, NULL, NULL, INTERNET_SERVICE_FTP, NULL, NULL); FtpSetCurrentDirectory(conn, PATH_FILE); FtpFindFirstFile(conn, NULL, &FileData, INTERNET_FLAG_NEED_FILE, NULL); FtpGetFile(conn, FileData->cFileName, LC_FILE, FALSE, FILE_ATTRIBUTE_NORMAL, FTP_TRANSFER_TYPE_BINARY, NULL); } } That code return error i know that because i do not identified memory on LPWIN32_FIND_DATA. But i do not know how do it.

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• the best way to convert delimited to fixed width

  - by ehosca

  What is the BEST way to convert this : FirstName,LastName,Title,BirthDate,HireDate,City,Region Nancy,Davolio,Sales Representative,1948-12-08,1992-05-01,Seattle,WA Andrew,Fuller,Vice President Sales,1952-02-19,1992-08-14,Tacoma,WA Janet,Leverling,Sales Representative,1963-08-30,1992-04-01,Kirkland,WA Margaret,Peacock,Sales Representative,1937-09-19,1993-05-03,Redmond,WA Steven,Buchanan,Sales Manager,1955-03-04,1993-10-17,London,NULL Michael,Suyama,Sales Representative,1963-07-02,1993-10-17,London,NULL Robert,King,Sales Representative,1960-05-29,1994-01-02,London,NULL Laura,Callahan,Inside Sales Coordinator,1958-01-09,1994-03-05,Seattle,WA Anne,Dodsworth,Sales Representative,1966-01-27,1994-11-15,London,NULL to this : FirstName LastName Title BirthDate HireDate City Region ---------- -------------------- ------------------------------ ----------- ---------- --------------- --------------- Nancy Davolio Sales Representative 1948-12-08 1992-05-01 Seattle WA Andrew Fuller Vice President, Sales 1952-02-19 1992-08-14 Tacoma WA Janet Leverling Sales Representative 1963-08-30 1992-04-01 Kirkland WA Margaret Peacock Sales Representative 1937-09-19 1993-05-03 Redmond WA Steven Buchanan Sales Manager 1955-03-04 1993-10-17 London NULL Michael Suyama Sales Representative 1963-07-02 1993-10-17 London NULL Robert King Sales Representative 1960-05-29 1994-01-02 London NULL Laura Callahan Inside Sales Coordinator 1958-01-09 1994-03-05 Seattle WA Anne Dodsworth Sales Representative 1966-01-27 1994-11-15 London NULL

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• Cross join (pivot) with n-n table containing values

  - by Styx31

  I have 3 tables : TABLE MyColumn ( ColumnId INT NOT NULL, Label VARCHAR(80) NOT NULL, PRIMARY KEY (ColumnId) ) TABLE MyPeriod ( PeriodId CHAR(6) NOT NULL, -- format yyyyMM Label VARCHAR(80) NOT NULL, PRIMARY KEY (PeriodId) ) TABLE MyValue ( ColumnId INT NOT NULL, PeriodId CHAR(6) NOT NULL, Amount DECIMAL(8, 4) NOT NULL, PRIMARY KEY (ColumnId, PeriodId), FOREIGN KEY (ColumnId) REFERENCES MyColumn(ColumnId), FOREIGN KEY (PeriodId) REFERENCES MyPeriod(PeriodId) ) MyValue's rows are only created when a real value is provided. I want my results in a tabular way, as : Column | Month 1 | Month 2 | Month 4 | Month 5 | Potatoes | 25.00 | 5.00 | 1.60 | NULL | Apples | 2.00 | 1.50 | NULL | NULL | I have successfully created a cross-join : SELECT MyColumn.Label AS [Column], MyPeriod.Label AS [Period], ISNULL(MyValue.Amount, 0) AS [Value] FROM MyColumn CROSS JOIN MyPeriod LEFT OUTER JOIN MyValue ON (MyValue.ColumnId = MyColumn.ColumnId AND MyValue.PeriodId = MyPeriod.PeriodId) Or, in linq : from p in MyPeriods from c in MyColumns join v in MyValues on new { c.ColumnId, p.PeriodId } equals new { v.ColumnId, v.PeriodId } into values from nv in values.DefaultIfEmpty() select new { Column = c.Label, Period = p.Label, Value = nv.Amount } And seen how to create a pivot in linq (here or here) : (assuming MyDatas is a view with the result of the previous query) : from c in MyDatas group c by c.Column into line select new { Column = line.Key, Month1 = line.Where(l => l.Period == "Month 1").Sum(l => l.Value), Month2 = line.Where(l => l.Period == "Month 2").Sum(l => l.Value), Month3 = line.Where(l => l.Period == "Month 3").Sum(l => l.Value), Month4 = line.Where(l => l.Period == "Month 4").Sum(l => l.Value) } But I want to find a way to create a resultset with, if possible, Month1, ... properties dynamic. Note : A solution which results in a n+1 query : from c in MyDatas group c by c.Column into line select new { Column = line.Key, Months = from l in line group l by l.Period into period select new { Period = period.Key, Amount = period.Sum(l => l.Value) } }

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• GetVirtualPath not making any sense.

  - by HeavyWave

  Can anyone explain why this code with the given routes returns the first route? routes.MapRoute(null, "user/approve", new { controller = "Users", action = "Approve" }), routes.MapRoute(null, "user/{username}", new { controller = "Users", action = "Profile" }), routes.MapRoute(null, "user/{username}/{action}", new { controller = "Users" }), routes.MapRoute(null, "user/{username}/{action}/{id}", new { controller = "Users" }), routes.MapRoute(null, "search/{query}", new { controller = "Artists", action = "Search", page = 1 }), routes.MapRoute(null, "search/{query}/{page}", new { controller = "Artists", action = "Search" }), routes.MapRoute(null, "music", new { controller = "Artists", action = "Index", page = 1 }), routes.MapRoute(null, "music/page/{page}", new { controller = "Artists", action = "Index" }) var pageLinkValueDictionary = new RouteValueDictionary(this.linkWithoutPageValuesDictionary); pageLinkValueDictionary.Add("page", pageNumber); var virtualPathData = RouteTable.Routes.GetVirtualPath(this.viewContext.RequestContext, pageLinkValueDictionary); Here GetVirtualPath always returns user/approve, although there is no {page} parameter in the route. Furthermore, everything works as expected without the first route. I have found this link http://www.codeplex.com/aspnet/WorkItem/View.aspx?WorkItemId=2033 but it wasn't very helpful. It looks like GetVirtualPath was not implemented with large collections of routes in mind. I am using ASP.Net MVC 1.0.

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• Problem with closing excel by c#

  - by phenevo

  Hi, I've got unit test with this code: Excel.Application objExcel = new Excel.Application(); Excel.Workbook objWorkbook = (Excel.Workbook)(objExcel.Workbooks._Open(@"D:\Selenium\wszystkieSeba2.xls", true, false, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value)); Excel.Worksheet ws = (Excel.Worksheet)objWorkbook.Sheets[1]; Excel.Range r = ws.get_Range("A1", "I2575"); DateTime dt = DateTime.Now; Excel.Range cellData = null; Excel.Range cellKwota = null; string cellValueData = null; string cellValueKwota = null; double dataTransakcji = 0; string dzien = null; string miesiac = null; int nrOperacji = 1; int wierszPoczatkowy = 11; int pozostalo = 526; cellData = r.Cells[wierszPoczatkowy, 1] as Excel.Range; cellKwota = r.Cells[wierszPoczatkowy, 6] as Excel.Range; if ((cellData != null) && (cellKwota != null)) { object valData = cellData.Value2; object valKwota = cellKwota.Value2; if ((valData != null) && (valKwota != null)) { cellValueData = valData.ToString(); dataTransakcji = Convert.ToDouble(cellValueData); Console.WriteLine("data transakcji to: " + dataTransakcji); dt = DateTime.FromOADate((double)dataTransakcji); dzien = dt.Day.ToString(); miesiac = dt.Month.ToString(); cellValueKwota = valKwota.ToString(); } } r.Cells[wierszPoczatkowy, 8] = "ok"; objWorkbook.Save(); objWorkbook.Close(true, @"C:\Documents and Settings\Administrator\Pulpit\Selenium\wszystkieSeba2.xls", true); objExcel.Quit(); Why after finish test I'm still having excel in process (it does'nt close) And : is there something I can improve to better perfomance ??

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• Formatting the code en-masse in Visual Studio

  - by AngryHacker

  I've inherited a project where all the private variables, and there are thousands, are separated by a blank line. For instance, private pnlSecurityReport _pnlSecurityReport = null; private pnlCalendar _pnlCalendar = null; private CtlContacts _pnlContacts = null; private pnlEmails _pnlEmails = null; private CtlNotes _pnlNotes = null; private pnlRoles _pnlRoles = null; private pnlSecurity _pnlSecurity = null; private pnlSignatures _pnlSignatures = null; This is really annoying. I'd like to remove the blank lines. Beyond writing my own tool to seek out and remove the extra line, is there a way to do this, perhaps, using RegEx-Fu in the Search and Replace dialog?

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• error in mysql syntax

  - by fusion

  while executing the following query, i get an error that there's an error in the syntax near line 9. since i'm using mysql workbench, i can't really figure out what could be wrong: CREATE TABLE IF NOT EXISTS `proquotes`.`thquotes` ( `idQuotes` INT NOT NULL AUTO_INCREMENT , `vAuthorID` VARCHAR(8) CHARACTER SET 'utf8' NOT NULL , `vAuthor` VARCHAR(45) CHARACTER SET 'utf8' NOT NULL , `cQuotes` MEDIUMTEXT CHARACTER SET 'utf8' NOT NULL , `cArabic` MEDIUMTEXT CHARACTER SET 'utf8' NOT NULL , `vReference` VARCHAR(100) CHARACTER SET 'utf8' NOT NULL , PRIMARY KEY (`idQuotes`) , INDEX `vAuthorID` () , CONSTRAINT `vAuthorID` FOREIGN KEY () REFERENCES `proquotes`.`author_info` () ON DELETE NO ACTION ON UPDATE NO ACTION) DEFAULT CHARACTER SET = utf8;

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• When anyDensity=false why does getDrawingCache(true) return null?

  - by Robert Nekic

  First off, my application currently defines anyDensity=false in the manifest file. Elsewhere in the app, I'm trying to capture and display a View's DrawingCache but I'm not able to get a clear Bitmap without scaling artifacts. The code below yields a Bitmap but it has scaling artifacts and is generally fuzzy. myView.setDrawingCacheEnabled(true); Bitmap myBitmap = Bitmap.Create(myView.getDrawingCache()); myImageView.setImageBitmap(myBitmap); As I read it, the documentation for getDrawingCache says this is to be expected and to use getDrawingCache(true). Yet, both code examples below throw NullPointer exceptions because the Bitmap returned by getDrawingCache(true) is always null. myView.setDrawingCacheEnabled(true); Bitmap myBitmap = Bitmap.Create(myView.getDrawingCache(true)); myImageView.setImageBitmap(myBitmap); OR myView.buildDrawingCache(true); Bitmap myBitmap = Bitmap.Create(myView.getDrawingCache(true)); myImageView.setImageBitmap(myBitmap); myView.destroyDrawingCache(); Does anyone know how to properly capture and render the drawingCache when anyDensity=false?

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• Java: volatile guarantees and out-of-order execution

  - by WizardOfOdds

  Note that this question is solely about the volatile keyword and the volatile guarantees: it is not about the synchronized keyword (so please don't answer "you must use synchronize" for I don't have any issue to solve: I simply want to understand the volatile guarantees (or lack of guarantees) regarding out-of-order execution). Say we have an object containing two volatile String references that are initialized to null by the constructor and that we have only one way to modify the two String: by calling setBoth(...) and that we can only set their references afterwards to non-null reference (only the constructor is allowed to set them to null). For example (it's just an example, there's no question yet): public class SO { private volatile String a; private volatile String b; public SO() { a = null; b = null; } public void setBoth( @NotNull final String one, @NotNull final String two ) { a = one; b = two; } public String getA() { return a; } public String getB() { return b; } } In setBoth(...), the line assigning the non-null parameter "a" appears before the line assigning the non-null parameter "b". Then if I do this (once again, there's no question, the question is coming next): if ( so.getB() != null ) { System.out.println( so.getA().length ); } Am I correct in my understanding that due to out-of-order execution I can get a NullPointerException? In other words: there's no guarantee that because I read a non-null "b" I'll read a non-null "a"? Because due to out-of-order (multi)processor and the way volatile works "b" could be assigned before "a"? volatile guarantees that reads subsequent to a write shall always see the last written value, but here there's an out-of-order "issue" right? (once again, the "issue" is made on purpose to try to understand the semantics of the volatile keyword and the Java Memory Model, not to solve a problem).

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• Why do the overloads of String.Format exist?

  - by GiddyUpHorsey

  I was using Reflector to look at the implementation of String.Format and had always been under the impression that the overloads of String.Format that took 1, 2 & 3 arguments were optimized versions of the method that takes an object array. However, what I found was that internally they create an object array and then call a method that takes an object array. 1 arg public static string Format(string format, object arg0) { if (format == null) { throw new ArgumentNullException("format"); } return Format(null, format, new object[] { arg0 }); } 2 args public static string Format(string format, object arg0, object arg1) { if (format == null) { throw new ArgumentNullException("format"); } return Format(null, format, new object[] { arg0, arg1 }); } 3 args public static string Format(string format, object arg0, object arg1, object arg2) { if (format == null) { throw new ArgumentNullException("format"); } return Format(null, format, new object[] { arg0, arg1, arg2 }); } Object array public static string Format(string format, params object[] args) { if ((format == null) || (args == null)) { throw new ArgumentNullException((format == null) ? "format" : "args"); } return Format(null, format, args); } Internally they all end up using the same code and so using the 1, 2 & 3 argument versions are no faster than the object array version. So my question is - why do they exist? When you use the object array version with a comma separated list of values, the compiler automatically converts the arguments into an object array because of the params/ParamArray keyword which is essentially what the 1, 2 & 3 versions do, so they seem redundant. Why did the BCL designers add these overloads?

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• sql 2008 sqldmo alternative

  - by alexdelpiero

  Hi! I previously was using sqldmo to automatically generate scripts from the databse. Now I upgraded to sql server 2008 and I don’t want to use this feature anymore since Microsoft will be dropping this feature off. Is there any other alternative I can use to connect to a server and generate scripts automatically from a database? Any answer is welcome. Thanks in advance. This is the procedure i was previously using: CREATE PROC GenerateSP ( @server varchar(30) = null, @uname varchar(30) = null, @pwd varchar(30) = null, @dbname varchar(30) = null, @filename varchar(200) = 'c:\script.sql' ) AS DECLARE @object int DECLARE @hr int DECLARE @return varchar(200) DECLARE @exec_str varchar(2000) DECLARE @spname sysname SET NOCOUNT ON -- Sets the server to the local server IF @server is NULL SELECT @server = @@servername -- Sets the database to the current database IF @dbname is NULL SELECT @dbname = db_name() -- Sets the username to the current user name IF @uname is NULL SELECT @uname = SYSTEM_USER -- Create an object that points to the SQL Server EXEC @hr = sp_OACreate 'SQLDMO.SQLServer', @object OUT IF @hr < 0 BEGIN PRINT 'error create SQLOLE.SQLServer' RETURN END -- Connect to the SQL Server IF @pwd is NULL BEGIN EXEC @hr = sp_OAMethod @object, 'Connect', NULL, @server, @uname IF @hr < 0 BEGIN PRINT 'error Connect' RETURN END END ELSE BEGIN EXEC @hr = sp_OAMethod @object, 'Connect', NULL, @server, @uname, @pwd IF @hr < 0 BEGIN PRINT 'error Connect' RETURN END END --Verify the connection EXEC @hr = sp_OAMethod @object, 'VerifyConnection', @return OUT IF @hr < 0 BEGIN PRINT 'error VerifyConnection' RETURN END SET @exec_str = 'DECLARE script_cursor CURSOR FOR SELECT name FROM ' + @dbname + '..sysobjects WHERE type = ''P'' ORDER BY Name' EXEC (@exec_str) OPEN script_cursor FETCH NEXT FROM script_cursor INTO @spname WHILE (@@fetch_status < -1) BEGIN SET @exec_str = 'Databases("'+ @dbname +'").StoredProcedures("'+RTRIM(UPPER(@spname))+'").Script(74077,"'+ @filename +'")' EXEC @hr = sp_OAMethod @object, @exec_str, @return OUT IF @hr < 0 BEGIN PRINT 'error Script' RETURN END FETCH NEXT FROM script_cursor INTO @spname END CLOSE script_cursor DEALLOCATE script_cursor -- Destroy the object EXEC @hr = sp_OADestroy @object IF @hr < 0 BEGIN PRINT 'error destroy object' RETURN END GO

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• Using DLL that using COM in C#

  - by chekalin-v

  I have been writing DLL on C++, that will be use in C#. DLL have some function, where I call hres = CoInitializeEx(NULL, COINIT_MULTITHREADED); and next call hres = CoInitializeSecurity( NULL, -1, // COM authentication NULL, // Authentication services NULL, // Reserved RPC_C_AUTHN_LEVEL_PKT, // Default authentication RPC_C_IMP_LEVEL_IMPERSONATE, // Default Impersonation NULL, // Authentication info EOAC_NONE, // Additional capabilities NULL // Reserved ); There are no error then I trying to use this dll in C++. But if I call function from DLL via C# application I see Error (80010106) Cannot change thread mode after it is set. I changed hres = CoInitializeEx(NULL, COINIT_MULTITHREADED); to hres = CoInitialize(NULL); After this changes error appear after CoInitializeSecurity: (80010119) Security must be initialized before any interfaces are marshalled or unmarshalled. It cannot be changed once initialized. How resolve this trouble?

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