invoke | 易学教程

Func<T>() vs Func<T>.Invoke()

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问题 I'm curious about the differences between calling a Func directly vs using Invoke() on it. Is there a difference ? Is the first, syntactical sugar, and calls Invoke() underneath anyway ? public T DoWork<T>(Func<T> method) { return (T)method.Invoke(); } vs public T DoWork<T>(Func<T> method) { return (T)method(); } Or am I on the wrong track entirely :) Thanks. 回答1: There's no difference at all. The second is just a shorthand for Invoke , provided by the compiler. They compile to the same IL.

C# Multithreading — Invoke without a Control

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问题 I am only somewhat familiar with multi-threading in that I've read about it but have never used it in practice. I have a project that uses a third party library that shares the status of an input device by raising events. The problem is, the way the library is written these events are raised from a different thread. My application does not need to be multi-threaded and I've run into a lot of classic threading issues (UI controls complaining about being interacted with from a different thread,

Ensuring that things run on the UI thread in WPF

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I'm building a WPF application. I'm doing some async communication with the server side, and I use event aggregation with Prism on the client. Both these things results in new threads to be spawned which are not the UI thread. If I attempt to do "WPF operations" on these callback and event handler threads the world will fall apart, which it now has started doing. First I met problems trying to create some WPF objects in the callback from server. I was told that the thread needed to run in STA mode. Now I'm trying to update some UI data in a Prism event handler, and I'm told that: The caller

How to execute a method passed as parameter to function

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问题 I want to write my own function in JavaScript which takes a callback method as a parameter and executes it after the completion, I don't know how to invoke a method in my method which is passed as an argument. Like Reflection. example code function myfunction(param1, callbackfunction) { //do processing here //how to invoke callbackfunction at this point? } //this is the function call to myfunction myfunction("hello", function(){ //call back method implementation here }); 回答1: You can just

Reflection MethodInfo.Invoke() catch exceptions from inside the method

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I have a call to MethodInfo.Invoke() to execute a function through reflection. The call is wrapped in a try/catch block but it still won't catch the exception thrown by the function I'm invoking. I receive the following message: Exception was unhandled by the user. Why does MethodInfo.Invoke() prevent the Exception to be caught outside of the Invoke() ? How do I bypass it? Ani EDIT: As I understand your issue, the problem is purely an IDE one; you don't like VS treating the exception thrown by the invocation of the MethodInfo as uncaught, when it clearly isn't. You can read about how to

Avoid calling Invoke when the control is disposed

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I have the following code in my worker thread ( ImageListView below is derived from Control ): if (mImageListView != null && mImageListView.IsHandleCreated && !mImageListView.IsDisposed) { if (mImageListView.InvokeRequired) mImageListView.Invoke( new RefreshDelegateInternal(mImageListView.RefreshInternal)); else mImageListView.RefreshInternal(); } However, I get an ObjectDisposedException sometimes with the Invoke method above. It appears that the control can be disposed between the time I check IsDisposed and I call Invoke . How can I avoid that? There are implicit race conditions in your

Communication between BroadcastReceiver and Activity - android

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I have a broadcast receiver in my app which is fired every time the user gets an incoming call. Now, when it happens, I need the broadcast receiver to invoke a specific method in a specific activity. Now, I tried to make this method static and therefore available, but something tells me it is a very bad idea. Accordingly, I tried to instantiate the broadcast receiver inside my activity without declaring it in my manifest but the problem is - when the app is off, the activity is not exist and therefore I can't invoke my method. So my question is - How can I invoke this method when the broadcast

“System.InvalidOperationException: The object is currently in use elsewhere” - how do I resolve this?

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问题 I got this error when trying to update an image. It was a cross-thread update, but I used .Invoke(), so that shouldn't be the problem, should it. 回答1: (Answering my own question, for others, and for future reference) I think (not yet entirely sure) that this is because InvokeRequired will always return false if the control has not yet been loaded/shown. I have done a workaround which seems to work for the moment, which is to simple reference the handle of the associated control in its creator

Invoking all setters within a class using reflection

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问题 I have a domain object, that for the purposes of this question I will call Person with the following private variables: String name int age Each of these have getters and setters. Now I also have a Map<String, String> with the following entries: name, phil age, 35 I would like to populate a list of all setter methods within the class Person and then looping through this list and invoking each method using the values from the map. Is this even possible as I cannot see any examples close to

Dispatcher Invoke(…) vs BeginInvoke(…) confusion

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I'm confused why I can't make this test counter application work with 2 (or more) simultaneous running countertextboxes with the use of "BeginInvoke" on my Dispatcher in the Count() method. You can solve the issue by replacing the BeginInvoke by an Invoke. But this doesn't solve my confusion. Here's the sample code I'm talking about: public class CounterTextBox : TextBox { private int _number; public void Start() { (new Action(Count)).BeginInvoke(null, null); } private void Count() { while (true) { if (_number++ > 10000) _number = 0; this.Dispatcher.BeginInvoke(new Action(UpdateText), System