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  • C++ - Where to code a member function for an inherited object.

    - by Francisco P.
    Hello! I have a few classes (heat, gas, contact, pressure) inheriting from a main one (sensor). I have a need to store them in a vector<Sensor *> (part of the specification). At some point in time, I need to call a function that indiscriminately stores those Sensor *. (also part of the specification, not open for discussion) Something like this: for(size_t i = 0; i < Sensors.size(); ++i) Sensors[i]->storeSensor(os) //os is an ofstream kind of object, passed onwards by reference Where and how shall storeSensor be defined? Is there any simple way to do this or will I need to disregard the specification? Mind you, I'm a beginner! Thanks for your time!

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  • How to show raw_id value of a ManyToMany relation in the Django admin?

    - by luc
    Hello, I have an app using raw_id on both ForeignKeyField and ManyToManyField. The admin displays the value of the foreign key on the right of the edit box. Unfortunatey, it doesn't work with ManyToMany. I've checked the code and I think that it is the normal behavior. However I would like to know if someone has an easy tip to change this behavior? Thanks in advance Update: I've tried to subclass the ManyToManyRawIdWidget but I don't know how to say that the raw_id_fields should use my custom widget. formfield_overrides doesn't seem to work with raw_id fields

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  • Javascript array value is undefined ... how do I test for that

    - by Ankur
    I am trying to test to see whether a Javascript variable is undefined. You will see that I am not expecting the value of predQuery[preId] to be 'undefined' if I don't first get an alert saying "its unbelievable". But I often do, so I am guessing that my statement predQuery[preId]=='undefined') is not matching the undefined elements properly. if((predQuery.length < preId) || (predQuery[preId]=="") || (predQuery[preId]=='undefined')){ alert("its unbelievable"); alert(predQuery[preId]); queryPreds[variables] = preId; queryObjs[variables] = objId; predQuery[preId] = variables; } else { alert(predQuery[preId]); var predIndex = predQuery[preId]; queryPreds[predIndex] = preId; queryObjs[predIndex] = objId; } I can add more code if needed.

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  • Sending a message from Objective-C and getting the return value?

    - by Nick Brooks
    I have this code NSString *tr = [self sendUrl:@"http://google.com/"]; But for some reason 'tr' will remain nil after it is executed. What am I doing wrong? sendUrl : - (NSString *)sendUrl:(NSString *) uri { NSLog(@"Requesting URI 1 ..."); // Prepare URL request to download statuses from Twitter NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:uri]]; NSLog(@"Requesting URI 2 ..."); // Perform request and get JSON back as a NSData object NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil]; NSLog(@"Requesting URI 3 ..."); // Get JSON as a NSString from NSData response NSString *json_string = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding]; NSLog(@"Requesting URI 4 ..."); return json_string; }

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  • How to check whether a mysql select statement result has a value or not in php?

    - by udaya
    I have a textbox UserName and a Check Availability button next to it..... I have checked the availability by passing UserName textbox value..... But it doesn't seem to work.... Here is what i am doing? echo $UserName = $_GET['CheckUsername']; $_SESSION['state'] = $State; $queryres = "SELECT dUser_name FROM tbl_login WHERE dUser_name='$UserName'"; $result = mysql_query($queryres,$cn) or die("Selection Query Failed !!!"); if($result==true) // this condition doesn't seem to work { echo "User Name Available"; } else { echo "Sorry user name taken"; }

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  • ListBox ,ScrollViewer ? CanContentScroll

    - by mrK
    Hi! I have ListBox with ScrollViewer <ScrollViewer Focusable="False" CanContentScroll="True" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Disabled"> <ListBox ItemsSource="{Binding Path=MyItems}" VerticalAlignment="Stretch" Focusable="False"> <ListBox.ItemContainerStyle> <Style TargetType="{x:Type ListBoxItem}"> <Setter Property="OverridesDefaultStyle" Value="true"/> <Setter Property="HorizontalContentAlignment" Value="Stretch"/> <Setter Property="VerticalContentAlignment" Value="Stretch"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type ListBoxItem}"> <Border CornerRadius="3,3,3,3"> <Grid> <myControls:MyControl/> </Grid> </Border> </ControlTemplate> </Setter.Value> </Setter> </Style> </ListBox.ItemContainerStyle> <ListBox.Style> <Style TargetType="ListBox"> <Setter Property="SnapsToDevicePixels" Value="true"/> <Setter Property="OverridesDefaultStyle" Value="true"/> <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/> <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/> <Setter Property="ScrollViewer.CanContentScroll" Value="True"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="ListBox"> <ScrollViewer Focusable="False" CanContentScroll="True"> <Border> <StackPanel Margin="2" Orientation="Horizontal" IsItemsHost="True"/> </Border> </ScrollViewer> </ControlTemplate> </Setter.Value> </Setter> </Style> </ListBox.Style> </ListBox> </ScrollViewer> But CanContentScroll="True" does't work. It's still scrolling in physical units. Whats wrong in my code? Thanks!

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  • Javascript: How to filter object array based on attributes?

    - by JGreig
    I have the following JavaScript JSON array of real estate home objects: var json = { 'homes' : [ { "home_id":"1", "price":"925", "sqft":"1100", "num_of_beds":"2", "num_of_baths":"2.0", }, { "home_id":"2", "price":"1425", "sqft":"1900", "num_of_beds":"4", "num_of_baths":"2.5", }, // ... (more homes) ... ]} var xmlhttp = eval('(' + json + ')'); homes = xmlhttp.homes; What I would like to do is be able to perform a filter on the object to return a subset of "home" objects. For example, I want to be able to filter based on: price, sqft, num_of_beds, and num_of_baths. Question: How can I perform something in javascript like the pseudo-code below: var newArray = homes.filter( price <= 1000 & sqft >= 500 & num_of_beds >=2 & num_of_baths >= 2.5); Note, the syntax does not have to be exactly like above. This is just an example.

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  • How to pass int value to a ajax enabled wcf service method?

    - by Pandiya Chendur
    I am calling an ajax enabled wcf service method from my aspx page... <script type="text/javascript"> function GetEmployee() { Service.GetEmployeeData('1','5',onGetDataSuccess); } function onGetDataSuccess(result) { Iteratejsondata(result) } </script> and my method doesn't seem to get the value [OperationContract] public string GetEmployeeData(int currentPage,int pageSize) { DataSet dt = GetEmployeeViewData(currentPage,pageSize); return GetJSONString(dt.Tables[0]); } when i used a break point to see what is happening in my method currentPage has a value0x00000001 and pageSize has 0x00000005 Any suggestion what am i doing wrong....

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  • What value should .net SqlCommand.ExecuteNonQuery() return if no rows are affected?

    - by peacedog
    I have the following code: int result = -1; StringBuilder sb = new StringBuilder(); SqlCommand cmd = MyConnection. sb.AppendLine("delete from Table1 where ID in"); sb.AppendLine("(select id from Table1 t1 where not exists(select * from Table2 t2 where t2.Table1ID = t1.ID))"); cmd.CommandText = sb.ToString(); result = cmd.ExecuteNonQuery(); _log.Info("StoredXMLDocument Records Deleted: " + result.ToString()); That SQL, in a more readable format, is: delete from Table1 where ID in (select id from Table1 t1 where not exists(select * from Table2 t2 where t2.Table1ID = t1.ID)) I know that the SQL, when executed directly in the database, deletes no rows. When this code runs, however, result gets a value of 1. I was expecting it to be 0. Am I missing something? Why is it 1?

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  • How to change the overlapping order of TabItems in WPF TabControl

    - by sannoble
    I have created vertical TabItems with a Path object. The selected TabItem overlaps the unselected TabItems, this works fine. The overlapping is done by setting a negative margin in the TabItem Template. For the unselected TabItems right now a TabItem is overlapped by the TabItem below. For example in the picture Tab 4 overlaps Tab 3 and Tab 3 overlaps Tab 2. I would like to change the overlapping order for the unselected Tab Items, so that an unselected TabItem overlaps the TabItem below and is overlapped by the TabItem above, e.g. Tab 2 overlaps Tab 3 and Tab 3 overlaps Tab 4. I have tried to set the FlowDirection property of TabPanel, but this doesn't work. How can I achieve this? Any help is appreciated. Thanks in advance! Wrong overlapping of unselected TabItems: XAML-Code: <Style x:Key="styleMainNavTabControl" TargetType="{x:Type TabControl}"> <Setter Property="TabStripPlacement" Value="Left" /> <Setter Property="SnapsToDevicePixels" Value="true"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type TabControl}"> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="*" /> <ColumnDefinition Width="200"/> </Grid.ColumnDefinitions> <Border Grid.Column="0" Background="White" BorderBrush="Black" BorderThickness="0,0,1,0" Padding="20"> <ContentPresenter ContentSource="SelectedContent" /> </Border> <Border Grid.Column="1" Padding="0,30,10,0" Background="#F7F3F7"> <TabPanel Panel.ZIndex="1" Margin="-1,0,0,0" FlowDirection="RightToLeft" IsItemsHost="True" Background="Transparent"/> </Border> </Grid> </ControlTemplate> </Setter.Value> </Setter> </Style> <Style x:Key="styleMainNavTabItem" TargetType="{x:Type TabItem}"> <Setter Property="MinHeight" Value="90" /> <Setter Property="FontSize" Value="14" /> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type TabItem}"> <Grid Margin="0,0,0,-35"> <Path Name="TabPath" Stroke="Black" StrokeThickness="1" Fill="LightGray" Data="M 0,0 a 10,10 0 0 0 10,10 h 150 a 20,20 0 0 1 20,20 v 60 a 20,20 0 0 1 -20,20 h -150 a 10,10 0 0 0 -10,10 z" /> <ContentPresenter ContentSource="Header" Margin="10,2,10,2" VerticalAlignment="Center" TextElement.Foreground="#FF000000"/> </Grid> <ControlTemplate.Triggers> <Trigger Property="IsSelected" Value="True"> <Setter Property="Panel.ZIndex" Value="100" /> <Setter TargetName="TabPath" Property="Fill" Value="White" /> <Setter TargetName="TabPath" Property="Data" Value="M 0,0 a 10,10 0 0 0 10,10 h 150 a 20,20 0 0 1 20,20 v 60 a 20,20 0 0 1 -20,20 h -150 a 10,10 0 0 0 -10,10" /> </Trigger> <Trigger Property="IsSelected" Value="False"> <Setter Property="Panel.ZIndex" Value="90" /> </Trigger> </ControlTemplate.Triggers> </ControlTemplate> </Setter.Value> </Setter>

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  • Dictionary w/ null key?

    - by Ralph
    Firstly, why doesn't Dictionary<TKey, TValue> support a single null key? Secondly, is there an existing dictionary-like collection that does? I want to store an "empty" or "missing" or "default" System.Type, thought null would work well for this. More specifically, I've written this class: class Switch { private Dictionary<Type, Action<object>> _dict; public Switch(params KeyValuePair<Type, Action<object>>[] cases) { _dict = new Dictionary<Type, Action<object>>(cases.Length); foreach (var entry in cases) _dict.Add(entry.Key, entry.Value); } public void Execute(object obj) { var type = obj.GetType(); if (_dict.ContainsKey(type)) _dict[type](obj); } public static void Execute(object obj, params KeyValuePair<Type, Action<object>>[] cases) { var type = obj.GetType(); foreach (var entry in cases) { if (entry.Key == null || type.IsAssignableFrom(entry.Key)) { entry.Value(obj); break; } } } public static KeyValuePair<Type, Action<object>> Case<T>(Action action) { return new KeyValuePair<Type, Action<object>>(typeof(T), x => action()); } public static KeyValuePair<Type, Action<object>> Case<T>(Action<T> action) { return new KeyValuePair<Type, Action<object>>(typeof(T), x => action((T)x)); } public static KeyValuePair<Type, Action<object>> Default(Action action) { return new KeyValuePair<Type, Action<object>>(null, x => action()); } } For switching on types. There are two ways to use it: Statically. Just call Switch.Execute(yourObject, Switch.Case<YourType>(x => x.Action())) Precompiled. Create a switch, and then use it later with switchInstance.Execute(yourObject) Works great except when you try to add a default case to the "precompiled" version (null argument exception).

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  • Java - What's the most efficient way of removing a set of elements from an Array[]

    - by fraido
    I've something like this Object[] myObjects = ...(initialized in some way)... int[] elemToRemove = new int[]{3,4,6,8,...} What's the most efficient way of removing the elements of index position 3,4,6,8... from myObjects ? I'd like to implement an efficient Utility method with a signature like public Object[] removeElements(Object[] object, int[] elementsToRemove) {...} The Object[] that is returned should be a new Object of size myObjects.length - elemToRemove.length

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  • how to find specific XML data by attribute name/value in flash AS2?

    - by CCrawler
    Given the following XML code: <set name="thumbsBooks"> <set name="pdf"> <thumb>Data I want to access</thumb> <thumb>Data I want to access</thumb> </set> <set name="printed"> <thumb>Data I don't want to access</thumb> <thumb>Data I don't want to access</thumb> </set> <set> I want to be able to get the data contained in the "thumb" tags using the "name" attribute value of the parent tag as a selector, something like you would do in jQuery: $('set[name="pdf"]').find('thumb'); Is there a method like this in Action Script 2 (can't use AS3)?

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  • NSManagedObject How To Reload

    - by crissag
    I have a view that consists of a table of existing objects and an Add button, which allows the user to create a new object. When the user presses Add, the object is created in the list view controller, so that the object will be part of that managed object context (via the NSEntityDescription insertNewObjectForEntityForName: method). The Add view has a property for the managed object. In the list view controller, I create an Add view controller, set the property to the managed object I created, and then push the Add view on to the navigation stack. In the Add view, I have two buttons for save and cancel. In the save, I save the managed object and pass the managed object back to the list view controller via a delegate method. If the user cancels, then I delete the object and pass nil back to the list view controller. The complication I am having in the add view is related to a UIImagePickerController. In the Add view, I have a button which allows the user to take a photo of the object (or use an existing photo from the photo library). However, the process of transferring to the UIImagePickerController and having the user use the camera, is resulting in a didReceiveMemoryWarning in the add view controller. Further, the view was unloaded, which also caused my NSManagedObject to get clobbered. My question is, how to you go about reloading the NSManagedObject in the case where it was released because of the low memory situation?

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  • Button to add value to array and then compare result with another array on IPhone.

    - by slickplaid
    I have ten buttons that each correspond to a different number. I'm looking to record the order that these buttons are pressed and enter them into an array and then compare it to another array that is static in the app. The check should be done on the Nth button press, where N equals the number of items in the other, static array. How do I A) have a button press add a value to an array B) stop after Nth button press equal to amount of numbers in the array I'm checking against and C) compare this array to the other array?

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  • How do i make a copy of an object? Javascript

    - by acidzombie24
    I have a class in json format. I would like to make two instance. Right now (its pretty obvious why) when i 'make' two objects i really have 2 vars pointing to one. (b.blah = 'z' will make a.blah=='z') How do i make a copy of an object? var template = { blah: 0, init: function (storageObj) { blah = storageObj; return this; //problem here }, func2: function (tagElement) { }, } a = template.init($('form [name=data]').eq(0)); b = template.init($('form [name=data2]').eq(0));

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  • In SQL how do I get the maximum value for an integer?

    - by CoffeeMonster
    Hi, I am trying to find out the maximum value for an integer (signed or unsigned) from a MySQL database. Is there a way to pull back this information from the database itself? Are there any built-in constants or functions I can use (either standard SQL or MySQL specific). At http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html it lists the values - but is there a way for the database to tell me. The following gives me the MAX_BIGINT - what I'd like is the MAX_INT. SELECT CAST( 99999999999999999999999 AS SIGNED ) as max_int; # max_int | 9223372036854775807 Thanks in advance,

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  • scroll into view the selected element

    - by yb007
    hi all, i am a newbie to javascript... i have two select boxes with multiple selection enabled.When i select an element from first select box it scrolls into view the corrosponding element from the second list.The single selection goes fine in all browsers explorer,firefox,chrome. now, if i select the first,last element from the first selection box the second select box does not scrolls into view the last selected element in chrome browser.although , it works fine in internet explorer and firefox. Please help me to make it run in google chrome browser. <html> <head> <script language="javascript"> function SyncListsL(){ for (var i = 0; i <= [document.puser.user_select.length]-1; i++) { if(document.puser.user_select.options[i].selected == true) { document.puser.user_select2.options[i].selected=true; document.puser.user_select.options[i].selected=true; } else{ document.puser.user_select2.options[i].selected = false; document.puser.user_select.options[i].selected=false; } } } function SyncListsR(){ for (i = 0; i <= [document.puser.user_select2.length]-1; i++) { if(document.puser.user_select2.options[i].selected == true) { document.puser.user_select.options[i].selected=true; document.puser.user_select2.options[i].selected=true; } else{ document.puser.user_select.options[i].selected = false; document.puser.user_select2.options[i].selected=false; } } } </script> <title>scrollintoview</title> </head> <body bgcolor="e2dbc5"> <form name="puser" > <table align="center"> <tr> <td align="right" bgcolor="#eeeadd"> <font size=2> <select name="user_select2" multiple size="5" onChange="SyncListsR()" style="width:35mm"> <option value="a1" title="a1">a1</option> <option value="a2" title="a2">a2</option> <option value="ab" title="ab">ab</option> <option value="abc" title="abc">abc</option> <option value="e1" title="e1">e1</option> <option value="e2" title="e2">e2</option> <option value="new" title="new">new</option> </select> </font></td> <td align="left" bgcolor="#eeeadd"> <font size=2> <select name="user_select" multiple size="5" onChange="SyncListsL()" style="width:50mm"> <option value="first" title="first">first</option> <option value="last" title="last">last</option> <option value="ghi" title="ghi">ghi</option> <option value="User" title="User">User</option> <option value="ed" title="ed">ed</option> <option value="edit" title="edit">edit</option> <option value="second" title="second">second</option> </select> </font></td> </tr> </table> </form> </body> </html>

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  • How to get two different array checkbox value in Jquery?.

    - by boss
    Hi.. For example i have 5 checkbox, 3 checkbox with name=a[] and 2 checkbox with name=b[], if i checked array a[] 3checkbox iam getting the same value for b[] checkbox even b[] checkbox not checked. please suggest... For ur reference: var selectedAItems = new Array(); $("input[@name='a[]']:checked").each(function() { selectedAItems.push($(this).val()); }); var selectedBItems = new Array(); $("input[@name='b[]']:checked").each(function() { selectedBItems.push($(this).val()); }); alert(selectedAItems); alert(selectedBItems );

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  • Python code to do csv file row entries comparison operations and count the number of times row value

    - by Venomancer
    have an excel based CSV file with two columns (or rows, Pythonically) that I am working on. What I need to do is to perform some operations so that I can compare the two data entries in each 'row'. To be more precise, one column has constant numbers all the way down, whereas the other column has varying values. So I need to count the number of times the varying column data entry values crosses the constant value on the other column. For example, fro the csv file i have two columns: Varying Column; Constant Column 24 25 26 25 crossed 27 25 26 25 25.5 25 23 25 crossed 26 25 crossed Thus, the varying column data entries have crossed 25 three times. I need to generate a code that can count the number of the crosses. Please do help out, Thanks.

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  • Anyway to get a value similar to @@ROWCOUNT when TOP is used?

    - by cfeduke
    If I have a SQL statement such as: SELECT TOP 5 * FROM Person WHERE Name LIKE 'Sm%' ORDER BY ID DESC PRINT @@ROWCOUNT -- shows '5' Is there anyway to get a value like @@ROWCOUNT that is the actual count of all of the rows that match the query without re-issuing the query again sans the TOP 5? The actual problem is a much more complex and intensive query that performs beautifully since we can use TOP n or SET ROWCOUNT n but then we cannot get a total count which is required to display paging information in the UI correctly. Presently we have to re-issue the query with a @Count = COUNT(ID) instead of *.

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  • Custom progress bar label text via binding

    - by Alexander K
    I was playing with progress bar customization in Silverlight application. What I want to reach is to have progress bar label to show current its state in the following format: "Value / Maximum". So, user will see what is the current value, and what is the maximum possible value. Here is a style for progress bar I use: <Style x:Key="ProgressBarStyle" TargetType="ProgressBar"> <Setter Property="Width" Value="97.21" /> <Setter Property="Height" Value="19" /> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="ProgressBar"> <Canvas x:Name="LevelField" Width="99" Height="21"> ... <TextBlock ... DataContext="{TemplateBinding Value}" Text="{Binding Converter={StaticResource DecNumberToStringConverter}}"/> </Canvas> </ControlTemplate> </Setter.Value> </Setter> </Style> The way I want to implement this, is to have a value converter, that will convert current value and maximum possible into the proper string. It does work properly, if it is written like above. However, I also need to provide ConverterParameter for Convertor, but not sure how to make it. When I write like this: , ConvertParameter={Binding Maximum}, it shows error on start, that Text attribute is not found in TextBlock. I was also trying to set DataContext as {RelativeSource Self}, but then it didn't displays error that DataContext attribute is not found. How to make the described progress bar label properly?

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  • php: parsing and converting array structure

    - by mwb
    I need to convert one array structure into another array structure. I hope someone will find it worthy their time to show how this could be done in a simple manner. It's a little above my array manipulation skills. The structure we start out with looks like this: $cssoptions = array( array( 'group' => 'Measurements' , 'selector' => '#content' , 'rule' => 'width' , 'value' => '200px' ) // end data set , array( 'group' => 'Measurements' , 'selector' => '#content' , 'rule' => 'margin-right' , 'value' => '20px' ) // end data set , array( 'group' => 'Colors' , 'selector' => '#content' , 'rule' => 'color' , 'value' => '#444' ) // end data set , array( 'group' => 'Measurements' , 'selector' => '.sidebar' , 'rule' => 'margin-top' , 'value' => '10px' ) // end data set ); // END $cssoptions It's a collection of discreet datasets, each consisting of an array that holds two key = value pairs describing a 'css-rule' and a 'css-rule-value'. Further, each dataset holds a key = value pair describing the 'css-selector-group' that the 'css-rule' should blong to, and a key = value pair describing a 'rule-group' that should be used for structuring the rendering of the final css into a neat css code block arranged by the kind of properties they describe (colors, measurement, typography etc..) Now, I need to parse that, and turn it into a new structure, where the: 'rule' => 'rule-name' , 'value' => 'value-string' for each dataset is converted into: 'rule-name' => 'value-string' ..and then placed into a new array structure where all 'rule-name' = 'value-string' pairs should be aggregated under the respective 'selector-values' Like this: '#content' => array( 'width' => '200px' , 'margin-right' => '20px' ) // end selecor block ..and finally all those blocks should be grouped under their respective 'style-groups', creating a final resulting array structure like this: $css => array( 'Measurements' => array( '#content' => array( 'width' => '200px' , 'margin-right' => '20px' ) // end selecor block , '.sidebar' => array( 'margin-top' => '10px' ) // end selector block ) // end rule group , 'Colors' => array( '#content' => array( 'color' => '#444' ) // end selector block ) // end rule group ); // end css

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  • How to reserve public API to internal usage in .NET?

    - by mark
    Dear ladies and sirs. Let me first present the case, which will explain my question. This is going to be a bit long, so I apologize in advance :-). I have objects and collections, which should support the Merge API (it is my custom API, the signature of which is immaterial for this question). This API must be internal, meaning only my framework should be allowed to invoke it. However, derived types should be able to override the basic implementation. The natural way to implement this pattern as I see it, is this: The Merge API is declared as part of some internal interface, let us say IMergeable. Because the interface is internal, derived types would not be able to implement it directly. Rather they must inherit it from a common base type. So, a common base type is introduced, which would implement the IMergeable interface explicitly, where the interface methods delegate to respective protected virtual methods, providing the default implementation. This way the API is only callable by my framework, but derived types may override the default implementation. The following code snippet demonstrates the concept: internal interface IMergeable { void Merge(object obj); } public class BaseFrameworkObject : IMergeable { protected virtual void Merge(object obj) { // The default implementation. } void IMergeable.Merge(object obj) { Merge(obj); } } public class SomeThirdPartyObject : BaseFrameworkObject { protected override void Merge(object obj) { // A derived type implementation. } } All is fine, provided a single common base type suffices, which is usually true for non collection types. The thing is that collections must be mergeable as well. Collections do not play nicely with the presented concept, because developers do not develop collections from the scratch. There are predefined implementations - observable, filtered, compound, read-only, remove-only, ordered, god-knows-what, ... They may be developed from scratch in-house, but once finished, they serve wide range of products and should never be tailored to some specific product. Which means, that either: they do not implement the IMergeable interface at all, because it is internal to some product the scope of the IMergeable interface is raised to public and the API becomes open and callable by all. Let us refer to these collections as standard collections. Anyway, the first option screws my framework, because now each possible standard collection type has to be paired with the respective framework version, augmenting the standard with the IMergeable interface implementation - this is so bad, I am not even considering it. The second option breaks the framework as well, because the IMergeable interface should be internal for a reason (whatever it is) and now this interface has to open to all. So what to do? My solution is this. make IMergeable public API, but add an extra parameter to the Merge method, I call it a security token. The interface implementation may check that the token references some internal object, which is never exposed to the outside. If this is the case, then the method was called from within the framework, otherwise - some outside API consumer attempted to invoke it and so the implementation can blow up with a SecurityException. Here is the modified code snippet demonstrating this concept: internal static class InternalApi { internal static readonly object Token = new object(); } public interface IMergeable { void Merge(object obj, object token); } public class BaseFrameworkObject : IMergeable { protected virtual void Merge(object obj) { // The default implementation. } public void Merge(object obj, object token) { if (!object.ReferenceEquals(token, InternalApi.Token)) { throw new SecurityException("bla bla bla"); } Merge(obj); } } public class SomeThirdPartyObject : BaseFrameworkObject { protected override void Merge(object obj) { // A derived type implementation. } } Of course, this is less explicit than having an internally scoped interface and the check is moved from the compile time to run time, yet this is the best I could come up with. Now, I have a gut feeling that there is a better way to solve the problem I have presented. I do not know, may be using some standard Code Access Security features? I have only vague understanding of it, but can LinkDemand attribute be somehow related to it? Anyway, I would like to hear other opinions. Thanks.

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  • I want to exchange the Value of a column in two different rows in Microsoft SQL server

    - by Silmaril89
    Hi, I want to do the following two SQL Queries in Microsoft SQL SERVER UPDATE Partnerships SET sortOrder = 2 WHERE sortOrder = 1; UPDATE Partnerships SET sortOrder = 1 WHERE sortOrder = 2; The only problem is, I don't allow for sortOrder to contain the same value, it is a unique key. How could I get around this, because the first query violates the unique key rule and terminates? Or will I have to get rid of the unique key rule I have? Thanks!

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