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  • Is there a method I can override on a JavaScript object to control what is displayed by console.log?

    - by agnoster
    I'm thinking in particular of Chrome, though Firebug would be interesting to. I've tried toString() and valueOf(), but neither of those seem to be used. Interestingly, if I take a function it'll display the function definition - but then if I add a toString() method it will show null! var a = function(){}; console.log(a); // output: function (){} a.toString = function(){ return 'a'; }; console.log(a); // output: null a.valueOf = function(){ return 'v'; }; console.log(a); // output: null Any ideas?

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  • How do I do a .count on the model an object belongs_to in rails?

    - by Angela
    I have @contacts_added defined as follows: @contacts_added = Contact.all(:conditions => ["date_entered >?", 5.days.ago.to_date]) Each contact belongs_to a Company. I want to be able the count the number of distinct Companies that @contacts_added belong to. contacts_added will have many contacts that belong to a single company, accessible through a virtual attribute contacts_added.company_name How do I do that?

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  • Are there any "gotchas" to watch for in using a Class (object) within itself?

    - by Clay Nichols
    I've got a Registry class and there are a few Registry values that I want to access from within that Registry class. (There is a bit of a calculation with these values so I thought I'd just put all that code right in the Registry Class itself). So we might have something within our RegistryRoutine.cls like: Function GetMyValue() as integer Dim R as new RegistryRoutine <calculations> GetMyValue=R.GetRegisetryValue (HKEY, key, value, etc.) End Function

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  • What is Rails way to DRY up the controller pattern of verifying :id is for a valid object (else redirect to error page)

    - by jpwynn
    One of my controllers has close to 100 methods (eg routes) and nearly every one starts out the same code to redirect to an error page if the id param is invalid, followed by a similar check if the user that id doesn't belong in the user's account: def something @foo = Foo.find_by_guid(params[:id]) unless @foo @msg ||= { :title => 'No such page!', :desc => "There is no such page!" } render :action => "error" and return end unless @foo.owner_id == current_user.id @msg ||= { :title => 'Really?', :desc => "There is no such page." } render :action => "error" and return end What is the best way to DRY up that sort of page id and owner id validation, given the code is doing a render ... and return? What I don't want to do at this point is offload it to a blackbox roles and permissions library like CanCan... my goal is simply to have the in-app code to handle this be as clean as possible.

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  • does xml ignores (,) OR (-)??? (xml of flash object).

    - by nectar
    <SCENE> <xml_image>telcos.jpg</xml_image> <xml_bigtext>TELCOS</xml_bigtext> <xml_smalltext>New-Age Properties, Wifi Everywhere</xml_smalltext> <xml_align>right</xml_align> <xml_bigtextcolor>#ffffff</xml_bigtextcolor> <xml_bigtextshadow>#0000000</xml_bigtextshadow> <xml_bigtextcolor>#ffffff</xml_bigtextcolor> <xml_bigtextshadow>#0000000</xml_bigtextshadow> this is the xml file of my flash.But ignores the highfun(-) and comma(,) like New-Age comes like NewAge and Properties, comes like PropertiesWifi WHY?

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  • AS3 - Can I have access to the object (or function) who call me?

    - by lk
    I've asked this same question with Python. Now I like to know if this can be done in AS3. If I have something like this: package { public class SomeClass { private function A():void { C() } private function B():void { C() } private function C():void { // who is the caller, A or B ??? } public function SomeClass() { A() B() } } } Despite the design or other issues, this is only a question of an inquiring mind. Note: This has to be done without changing C signature Note 2: I like to have an access to an instance of the caller function so I can call that caller function (if I want to)

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  • How to check the type name of an object in derived classes?

    - by Vincenzo
    This is my code: class Base { /* something */ }; class Derived : public Base { /* something */ }; vector<Base*> v; // somebody else initializes it, somewhere int counter = 0; for (vector<Base*>::iterator i=v.begin(); i!=v.end(); ++i) { if (typeof(*i) == "Derived") { // this line is NOT correct counter++; } } cout << "Found " << counter << " derived classes"; One line in the code is NOT correct. How should I write it properly? Many thanks in advance!

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  • C#/.NET Little Wonders: The Joy of Anonymous Types

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the .NET 3 Framework, Microsoft introduced the concept of anonymous types, which provide a way to create a quick, compiler-generated types at the point of instantiation.  These may seem trivial, but are very handy for concisely creating lightweight, strongly-typed objects containing only read-only properties that can be used within a given scope. Creating an Anonymous Type In short, an anonymous type is a reference type that derives directly from object and is defined by its set of properties base on their names, number, types, and order given at initialization.  In addition to just holding these properties, it is also given appropriate overridden implementations for Equals() and GetHashCode() that take into account all of the properties to correctly perform property comparisons and hashing.  Also overridden is an implementation of ToString() which makes it easy to display the contents of an anonymous type instance in a fairly concise manner. To construct an anonymous type instance, you use basically the same initialization syntax as with a regular type.  So, for example, if we wanted to create an anonymous type to represent a particular point, we could do this: 1: var point = new { X = 13, Y = 7 }; Note the similarity between anonymous type initialization and regular initialization.  The main difference is that the compiler generates the type name and the properties (as readonly) based on the names and order provided, and inferring their types from the expressions they are assigned to. It is key to remember that all of those factors (number, names, types, order of properties) determine the anonymous type.  This is important, because while these two instances share the same anonymous type: 1: // same names, types, and order 2: var point1 = new { X = 13, Y = 7 }; 3: var point2 = new { X = 5, Y = 0 }; These similar ones do not: 1: var point3 = new { Y = 3, X = 5 }; // different order 2: var point4 = new { X = 3, Y = 5.0 }; // different type for Y 3: var point5 = new {MyX = 3, MyY = 5 }; // different names 4: var point6 = new { X = 1, Y = 2, Z = 3 }; // different count Limitations on Property Initialization Expressions The expression for a property in an anonymous type initialization cannot be null (though it can evaluate to null) or an anonymous function.  For example, the following are illegal: 1: // Null can't be used directly. Null reference of what type? 2: var cantUseNull = new { Value = null }; 3:  4: // Anonymous methods cannot be used. 5: var cantUseAnonymousFxn = new { Value = () => Console.WriteLine(“Can’t.”) }; Note that the restriction on null is just that you can’t use it directly as the expression, because otherwise how would it be able to determine the type?  You can, however, use it indirectly assigning a null expression such as a typed variable with the value null, or by casting null to a specific type: 1: string str = null; 2: var fineIndirectly = new { Value = str }; 3: var fineCast = new { Value = (string)null }; All of the examples above name the properties explicitly, but you can also implicitly name properties if they are being set from a property, field, or variable.  In these cases, when a field, property, or variable is used alone, and you don’t specify a property name assigned to it, the new property will have the same name.  For example: 1: int variable = 42; 2:  3: // creates two properties named varriable and Now 4: var implicitProperties = new { variable, DateTime.Now }; Is the same type as: 1: var explicitProperties = new { variable = variable, Now = DateTime.Now }; But this only works if you are using an existing field, variable, or property directly as the expression.  If you use a more complex expression then the name cannot be inferred: 1: // can't infer the name variable from variable * 2, must name explicitly 2: var wontWork = new { variable * 2, DateTime.Now }; In the example above, since we typed variable * 2, it is no longer just a variable and thus we would have to assign the property a name explicitly. ToString() on Anonymous Types One of the more trivial overrides that an anonymous type provides you is a ToString() method that prints the value of the anonymous type instance in much the same format as it was initialized (except actual values instead of expressions as appropriate of course). For example, if you had: 1: var point = new { X = 13, Y = 42 }; And then print it out: 1: Console.WriteLine(point.ToString()); You will get: 1: { X = 13, Y = 42 } While this isn’t necessarily the most stunning feature of anonymous types, it can be handy for debugging or logging values in a fairly easy to read format. Comparing Anonymous Type Instances Because anonymous types automatically create appropriate overrides of Equals() and GetHashCode() based on the underlying properties, we can reliably compare two instances or get hash codes.  For example, if we had the following 3 points: 1: var point1 = new { X = 1, Y = 2 }; 2: var point2 = new { X = 1, Y = 2 }; 3: var point3 = new { Y = 2, X = 1 }; If we compare point1 and point2 we’ll see that Equals() returns true because they overridden version of Equals() sees that the types are the same (same number, names, types, and order of properties) and that the values are the same.   In addition, because all equal objects should have the same hash code, we’ll see that the hash codes evaluate to the same as well: 1: // true, same type, same values 2: Console.WriteLine(point1.Equals(point2)); 3:  4: // true, equal anonymous type instances always have same hash code 5: Console.WriteLine(point1.GetHashCode() == point2.GetHashCode()); However, if we compare point2 and point3 we get false.  Even though the names, types, and values of the properties are the same, the order is not, thus they are two different types and cannot be compared (and thus return false).  And, since they are not equal objects (even though they have the same value) there is a good chance their hash codes are different as well (though not guaranteed): 1: // false, different types 2: Console.WriteLine(point2.Equals(point3)); 3:  4: // quite possibly false (was false on my machine) 5: Console.WriteLine(point2.GetHashCode() == point3.GetHashCode()); Using Anonymous Types Now that we’ve created instances of anonymous types, let’s actually use them.  The property names (whether implicit or explicit) are used to access the individual properties of the anonymous type.  The main thing, once again, to keep in mind is that the properties are readonly, so you cannot assign the properties a new value (note: this does not mean that instances referred to by a property are immutable – for more information check out C#/.NET Fundamentals: Returning Data Immutably in a Mutable World). Thus, if we have the following anonymous type instance: 1: var point = new { X = 13, Y = 42 }; We can get the properties as you’d expect: 1: Console.WriteLine(“The point is: ({0},{1})”, point.X, point.Y); But we cannot alter the property values: 1: // compiler error, properties are readonly 2: point.X = 99; Further, since the anonymous type name is only known by the compiler, there is no easy way to pass anonymous type instances outside of a given scope.  The only real choices are to pass them as object or dynamic.  But really that is not the intention of using anonymous types.  If you find yourself needing to pass an anonymous type outside of a given scope, you should really consider making a POCO (Plain Old CLR Type – i.e. a class that contains just properties to hold data with little/no business logic) instead. Given that, why use them at all?  Couldn’t you always just create a POCO to represent every anonymous type you needed?  Sure you could, but then you might litter your solution with many small POCO classes that have very localized uses. It turns out this is the key to when to use anonymous types to your advantage: when you just need a lightweight type in a local context to store intermediate results, consider an anonymous type – but when that result is more long-lived and used outside of the current scope, consider a POCO instead. So what do we mean by intermediate results in a local context?  Well, a classic example would be filtering down results from a LINQ expression.  For example, let’s say we had a List<Transaction>, where Transaction is defined something like: 1: public class Transaction 2: { 3: public string UserId { get; set; } 4: public DateTime At { get; set; } 5: public decimal Amount { get; set; } 6: // … 7: } And let’s say we had this data in our List<Transaction>: 1: var transactions = new List<Transaction> 2: { 3: new Transaction { UserId = "Jim", At = DateTime.Now, Amount = 2200.00m }, 4: new Transaction { UserId = "Jim", At = DateTime.Now, Amount = -1100.00m }, 5: new Transaction { UserId = "Jim", At = DateTime.Now.AddDays(-1), Amount = 900.00m }, 6: new Transaction { UserId = "John", At = DateTime.Now.AddDays(-2), Amount = 300.00m }, 7: new Transaction { UserId = "John", At = DateTime.Now, Amount = -10.00m }, 8: new Transaction { UserId = "Jane", At = DateTime.Now, Amount = 200.00m }, 9: new Transaction { UserId = "Jane", At = DateTime.Now, Amount = -50.00m }, 10: new Transaction { UserId = "Jaime", At = DateTime.Now.AddDays(-3), Amount = -100.00m }, 11: new Transaction { UserId = "Jaime", At = DateTime.Now.AddDays(-3), Amount = 300.00m }, 12: }; So let’s say we wanted to get the transactions for each day for each user.  That is, for each day we’d want to see the transactions each user performed.  We could do this very simply with a nice LINQ expression, without the need of creating any POCOs: 1: // group the transactions based on an anonymous type with properties UserId and Date: 2: byUserAndDay = transactions 3: .GroupBy(tx => new { tx.UserId, tx.At.Date }) 4: .OrderBy(grp => grp.Key.Date) 5: .ThenBy(grp => grp.Key.UserId); Now, those of you who have attempted to use custom classes as a grouping type before (such as GroupBy(), Distinct(), etc.) may have discovered the hard way that LINQ gets a lot of its speed by utilizing not on Equals(), but also GetHashCode() on the type you are grouping by.  Thus, when you use custom types for these purposes, you generally end up having to write custom Equals() and GetHashCode() implementations or you won’t get the results you were expecting (the default implementations of Equals() and GetHashCode() are reference equality and reference identity based respectively). As we said before, it turns out that anonymous types already do these critical overrides for you.  This makes them even more convenient to use!  Instead of creating a small POCO to handle this grouping, and then having to implement a custom Equals() and GetHashCode() every time, we can just take advantage of the fact that anonymous types automatically override these methods with appropriate implementations that take into account the values of all of the properties. Now, we can look at our results: 1: foreach (var group in byUserAndDay) 2: { 3: // the group’s Key is an instance of our anonymous type 4: Console.WriteLine("{0} on {1:MM/dd/yyyy} did:", group.Key.UserId, group.Key.Date); 5:  6: // each grouping contains a sequence of the items. 7: foreach (var tx in group) 8: { 9: Console.WriteLine("\t{0}", tx.Amount); 10: } 11: } And see: 1: Jaime on 06/18/2012 did: 2: -100.00 3: 300.00 4:  5: John on 06/19/2012 did: 6: 300.00 7:  8: Jim on 06/20/2012 did: 9: 900.00 10:  11: Jane on 06/21/2012 did: 12: 200.00 13: -50.00 14:  15: Jim on 06/21/2012 did: 16: 2200.00 17: -1100.00 18:  19: John on 06/21/2012 did: 20: -10.00 Again, sure we could have just built a POCO to do this, given it an appropriate Equals() and GetHashCode() method, but that would have bloated our code with so many extra lines and been more difficult to maintain if the properties change.  Summary Anonymous types are one of those Little Wonders of the .NET language that are perfect at exactly that time when you need a temporary type to hold a set of properties together for an intermediate result.  While they are not very useful beyond the scope in which they are defined, they are excellent in LINQ expressions as a way to create and us intermediary values for further expressions and analysis. Anonymous types are defined by the compiler based on the number, type, names, and order of properties created, and they automatically implement appropriate Equals() and GetHashCode() overrides (as well as ToString()) which makes them ideal for LINQ expressions where you need to create a set of properties to group, evaluate, etc. Technorati Tags: C#,CSharp,.NET,Little Wonders,Anonymous Types,LINQ

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  • Enabling Service Availability in WCF Services

    - by cibrax
    It is very important for the enterprise to know which services are operational at any given point. There are many factors that can affect the availability of the services, some of them are external like a database not responding or any dependant service not working. However, in some cases, you only want to know whether a service is up or down, so a simple heart-beat mechanism with “Ping” messages would do the trick. Unfortunately, WCF does not provide a built-in mechanism to support this functionality, and you probably don’t to implement a “Ping” operation in any service that you have out there. For solving this in a generic way, there is a WCF extensibility point that comes to help us, the “Operation Invokers”. In a nutshell, an operation invoker is the class responsible invoking the service method with a set of parameters and generate the output parameters with the return value. What I am going to do here is to implement a custom operation invoker that intercepts any call to the service, and detects whether a “Ping” header was attached to the message. If the “Ping” header is detected, the operation invoker returns a new header to tell the client that the service is alive, and the real operation execution is omitted. In that way, we have a simple heart beat mechanism based on the messages that include a "Ping” header, so the client application can determine at any point whether the service is up or down. My operation invoker wraps the default implementation attached by default to any operation by WCF. internal class PingOperationInvoker : IOperationInvoker { IOperationInvoker innerInvoker; object[] outputs = null; object returnValue = null; public const string PingHeaderName = "Ping"; public const string PingHeaderNamespace = "http://tellago.serviceModel"; public PingOperationInvoker(IOperationInvoker innerInvoker, OperationDescription description) { this.innerInvoker = innerInvoker; outputs = description.SyncMethod.GetParameters() .Where(p => p.IsOut) .Select(p => DefaultForType(p.ParameterType)).ToArray(); var returnValue = DefaultForType(description.SyncMethod.ReturnType); } private static object DefaultForType(Type targetType) { return targetType.IsValueType ? Activator.CreateInstance(targetType) : null; } public object Invoke(object instance, object[] inputs, out object[] outputs) { object returnValue; if (Invoke(out returnValue, out outputs)) { return returnValue; } else { return this.innerInvoker.Invoke(instance, inputs, out outputs); } } private bool Invoke(out object returnValue, out object[] outputs) { object untypedProperty = null; if (OperationContext.Current .IncomingMessageProperties.TryGetValue(HttpRequestMessageProperty.Name, out untypedProperty)) { var httpRequestProperty = untypedProperty as HttpRequestMessageProperty; if (httpRequestProperty != null) { if (httpRequestProperty.Headers[PingHeaderName] != null) { outputs = this.outputs; if (OperationContext.Current .IncomingMessageProperties.TryGetValue(HttpRequestMessageProperty.Name, out untypedProperty)) { var httpResponseProperty = untypedProperty as HttpResponseMessageProperty; httpResponseProperty.Headers.Add(PingHeaderName, "Ok"); } returnValue = this.returnValue; return true; } } } var headers = OperationContext.Current.IncomingMessageHeaders; if (headers.FindHeader(PingHeaderName, PingHeaderNamespace) > -1) { outputs = this.outputs; MessageHeader<string> header = new MessageHeader<string>("Ok"); var untyped = header.GetUntypedHeader(PingHeaderName, PingHeaderNamespace); OperationContext.Current.OutgoingMessageHeaders.Add(untyped); returnValue = this.returnValue; return true; } returnValue = null; outputs = null; return false; } } The implementation above looks for the “Ping” header either in the Http Request or the Soap message. The next step is to implement a behavior for attaching this operation invoker to the services we want to monitor. [AttributeUsage(AttributeTargets.Method | AttributeTargets.Class, AllowMultiple = false, Inherited = true)] public class PingBehavior : Attribute, IServiceBehavior, IOperationBehavior { public void AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, Collection<ServiceEndpoint> endpoints, BindingParameterCollection bindingParameters) { } public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase) { } public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase) { foreach (var endpoint in serviceDescription.Endpoints) { foreach (var operation in endpoint.Contract.Operations) { if (operation.Behaviors.Find<PingBehavior>() == null) operation.Behaviors.Add(this); } } } public void AddBindingParameters(OperationDescription operationDescription, BindingParameterCollection bindingParameters) { } public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation) { } public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation) { dispatchOperation.Invoker = new PingOperationInvoker(dispatchOperation.Invoker, operationDescription); } public void Validate(OperationDescription operationDescription) { } } As an operation invoker can only be added in an “operation behavior”, a trick I learned in the past is that you can implement a service behavior as well and use the “Validate” method to inject it in all the operations, so the final configuration is much easier and cleaner. You only need to decorate the service with a simple attribute to enable the “Ping” functionality. [PingBehavior] public class HelloWorldService : IHelloWorld { public string Hello(string name) { return "Hello " + name; } } On the other hand, the client application needs to send a dummy message with a “Ping” header to detect whether the service is available or not. In order to simplify this task, I created a extension method in the WCF client channel to do this work. public static class ClientChannelExtensions { const string PingNamespace = "http://tellago.serviceModel"; const string PingName = "Ping"; public static bool IsAvailable<TChannel>(this IClientChannel channel, Action<TChannel> operation) { try { using (OperationContextScope scope = new OperationContextScope(channel)) { MessageHeader<string> header = new MessageHeader<string>(PingName); var untyped = header.GetUntypedHeader(PingName, PingNamespace); OperationContext.Current.OutgoingMessageHeaders.Add(untyped); try { operation((TChannel)channel); var headers = OperationContext.Current.IncomingMessageHeaders; if (headers.Any(h => h.Name == PingName && h.Namespace == PingNamespace)) { return true; } else { return false; } } catch (CommunicationException) { return false; } } } catch (Exception) { return false; } } } This extension method basically adds a “Ping” header to the request message, executes the operation passed as argument (Action<TChannel> operation), and looks for the corresponding “Ping” header in the response to see the results. The client application can use this extension with a single line of code, var client = new ServiceReference.HelloWorldClient(); var isAvailable = client.InnerChannel.IsAvailable<IHelloWorld>((c) => c.Hello(null)); The “isAvailable” variable will tell the client application whether the service is available or not. You can download the complete implementation from this location.    

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  • SharePoint 2010 Search Error 0x800703fa

    - by Ben
    We have migrated from SharePoint 2007 to 2010. Everything appears to be working correctly except for an intermitent error with search. Occastionally search results will crash for all of our sites and when we look up the coorliation id we get the following error: Exception when fetching results: System.ServiceModel.FaultException`1[System.ServiceModel.ExceptionDetail]: Illegal operation attempted on a registry key that has been marked for deletion. (Exception from HRESULT: 0x800703FA) (Fault Detail is equal to An ExceptionDetail, likely created by IncludeExceptionDetailInFaults=true, whose value is: System.Runtime.InteropServices.COMException: Illegal operation attempted on a registry key that has been marked for deletion. (Exception from HRESULT: 0x800703FA) at System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32 errorCode, IntPtr errorInfo) at Microsoft.Office.Server.Search.Query.KeywordQueryInternal.Execute() at Microsoft.Office.Server.Search.Query.QueryInternal.Execute(QueryProperties properties) at Microsoft.Office.Server.Search.Administration.SearchServiceApplication.Execute(QueryProperties properties) at SyncInvokeExecute(Object , Object[] , Object[] ) at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs) at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc) at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc) We reset IIS and the problem resolves itself for a while. Has anyone come across a perminant fix for this?

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  • Prevent ListBox from focusing but leave ListBoxItem(s) focusable (wpf)

    - by modosansreves
    Here is what happens: I have a listbox with items. Listbox has focus. Some item (say, 5th) is selected (has a blue background), but has no 'border'. When I press 'Down' key, the focus moves from ListBox to the first ListBoxItem. (What I want is to make 6th item selected, regardless of the 'border') When I navigate using 'Tab', the Listbox never receives the focus again. But when the collection is emptied and filled again, ListBox itself gets focus, pressing 'Down' moves the focus to the item. How to prevent ListBox from gaining focus? P.S. listBox1.SelectedItem is my own class, I don't know how to make ListBoxItem out of it to .Focus() it. EDIT: the code Xaml: <UserControl.Resources> <me:BooleanToVisibilityConverter x:Key="visibilityConverter"/> <me:BooleanToItalicsConverter x:Key="italicsConverter"/> </UserControl.Resources> <ListBox x:Name="lbItems"> <ListBox.ItemTemplate> <DataTemplate> <Grid> <ProgressBar HorizontalAlignment="Stretch" VerticalAlignment="Bottom" Visibility="{Binding Path=ShowProgress, Converter={StaticResource visibilityConverter}}" Maximum="1" Margin="4,0,0,0" Value="{Binding Progress}" /> <TextBlock Text="{Binding Path=VisualName}" FontStyle="{Binding Path=IsFinished, Converter={StaticResource italicsConverter}}" Margin="4" /> </Grid> </DataTemplate> </ListBox.ItemTemplate> <me:OuterItem Name="Regular Folder" IsFinished="True" Exists="True" IsFolder="True"/> <me:OuterItem Name="Regular Item" IsFinished="True" Exists="True"/> <me:OuterItem Name="Yet to be created" IsFinished="False" Exists="False"/> <me:OuterItem Name="Just created" IsFinished="False" Exists="True"/> <me:OuterItem Name="In progress" IsFinished="False" Exists="True" Progress="0.7"/> </ListBox> where OuterItem is: public class OuterItem : IOuterItem { public Guid Id { get; set; } public string Name { get; set; } public bool IsFolder { get; set; } public bool IsFinished { get; set; } public bool Exists { get; set; } public double Progress { get; set; } /// Code below is of lesser importance, but anyway /// #region Visualization helper properties public bool ShowProgress { get { return !IsFinished && Exists; } } public string VisualName { get { return IsFolder ? "[ " + Name + " ]" : Name; } } #endregion public override string ToString() { if (IsFinished) return Name; if (!Exists) return " ??? " + Name; return Progress.ToString("0.000 ") + Name; } public static OuterItem Get(IOuterItem item) { return new OuterItem() { Id = item.Id, Name = item.Name, IsFolder = item.IsFolder, IsFinished = item.IsFinished, Exists = item.Exists, Progress = item.Progress }; } } ?onverters are: /// Are of lesser importance too (for understanding), but will be useful if you copy-paste to get it working public class BooleanToItalicsConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { bool normal = (bool)value; return normal ? FontStyles.Normal : FontStyles.Italic; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { throw new NotImplementedException(); } } public class BooleanToVisibilityConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { bool exists = (bool)value; return exists ? Visibility.Visible : Visibility.Collapsed; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { throw new NotImplementedException(); } } But most important, is that UserControl.Loaded() has: lbItems.Items.Clear(); lbItems.ItemsSource = fsItems; where fsItems is ObservableCollection<OuterItem>. The usability problem I describe takes place when I Clear() that collection (fsItems) and fill with new items.

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  • Marshal a C# struct to C++ VARIANT

    - by jortan
    To start with, I'm not very familiar with the COM-technology, this is the first time I'm working with it so bear with me. I'm trying to call a COM-object function from C#. This is the interface in the idl-file: [id(6), helpstring("vConnectInfo=ConnectInfoType")] HRESULT ConnectTarget([in,out] VARIANT* vConnectInfo); This is the interop interface I got after running tlbimp: void ConnectTarget(ref object vConnectInfo); The c++ code in COM object for the target function: STDMETHODIMP PCommunication::ConnectTarget(VARIANT* vConnectInfo) { if (!((vConnectInfo->vt & VT_ARRAY) && (vConnectInfo->vt & VT_BYREF))) { return E_INVALIDARG; } ConnectInfoType *pConnectInfo = (ConnectInfoType *)((*vConnectInfo->pparray)->pvData); ... } This COM-object is running in another process, it is not in a dll. I can add that the COM object is also used from another program written in C++. In that case there is no problem because in C++ a VARIANT is created and pparray-pvData is set to the connInfo data-structure and then the COM-object is called with the VARIANT as parameter. In C#, as I understand, my struct should be marshalled as a VARIANT automatically. These are two methods I've been using (or actually I've tried a lot more...) to call this method from C#: private void method1_Click(object sender, EventArgs e) { pcom.PCom PCom = new pcom.PCom(); pcom.IGeneralManagementServices mgmt = (pcom.IGeneralManagementServices)PCom; m_ci = new ConnectInfoType(); fillConnInfo(ref m_ci); mgmt.ConnectTarget(m_ci); } In the above case the struct gets marshalled as VT_UNKNOWN. This is a simple case and works if the parameter is not a struct (eg. works for int). private void method4_Click(object sender, EventArgs e) { ConnectInfoType ci = new ConnectInfoType(); fillConnInfo(ref ci); pcom PCom = new pcom.PCom(); pcom.IGeneralManagementServices mgmt = (pcom.IGeneralManagementServices)PCom; ParameterModifier[] pms = new ParameterModifier[1]; ParameterModifier pm = new ParameterModifier(1); pm[0] = true; pms[0] = pm; object[] param = new object[1]; param[0] = ci; object[] args = new object[1]; args[0] = param; mgmt.GetType().InvokeMember("ConnectTarget", BindingFlags.InvokeMethod, null, mgmt, args, pms, null, null); } In this case it gets marshalled as VT_ARRAY | VT_BYREF | VT_VARIANT. The problem is that when debugging the "target-function" ConnectTarget I cannot find the data I send in the SAFEARRAY-struct (or in any other place in memory either) What do I do with a VT_VARIANT? Any ideas on how to get my struct-data? Update: The ConnectInfoType struct: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public class ConnectInfoType { public short network; public short nodeNumber; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 51)] public string connTargPassWord; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 8)] public string sConnectId; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)] public string sConnectPassword; public EnuConnectType eConnectType; public int hConnectHandle; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 8)] public string sAccessPassword; }; And the corresponding struct in c++: typedef struct ConnectInfoType { short network; short nodeNumber; char connTargPassWord[51]; char sConnectId[8]; char sConnectPassword[16]; EnuConnectType eConnectType; int hConnectHandle; char sAccessPassword[8]; } ConnectInfoType;

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