invoke

Invoking methods with optional parameters through reflection

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According to MSDN, to use the default parameter you should pass Type.Missing. If your constructor has three optional arguments then instead of passing an empty object array you’d pass a three element object array where each element’s value is Type.Missing, e.g. type.GetParameterlessConstructor() .Invoke(BindingFlags.OptionalParamBinding | BindingFlags.InvokeMethod | BindingFlags.CreateInstance, null, new object[] { Type.Missing, Type.Missing, Type.Missing }, … Read more

Cleaning up code littered with InvokeRequired [duplicate]

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Well how about this: public static class ControlHelpers { public static void InvokeIfRequired<T>(this T control, Action<T> action) where T : ISynchronizeInvoke { if (control.InvokeRequired) { control.Invoke(new Action(() => action(control)), null); } else { action(control); } } } Use it like this: private void UpdateSummary(string text) { summary.InvokeIfRequired(s => { s.Text = text }); }

How to get return value when BeginInvoke/Invoke is called in C#

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You have to Invoke() so you can wait for the function to return and obtain its return value. You’ll also need another delegate type. This ought to work: public static string readControlText(Control varControl) { if (varControl.InvokeRequired) { return (string)varControl.Invoke( new Func<String>(() => readControlText(varControl)) ); } else { string varText = varControl.Text; return varText; } }

MethodInvoker vs Action for Control.BeginInvoke

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Both are equally correct, but the documentation for Control.Invoke states that: The delegate can be an instance of EventHandler, in which case the sender parameter will contain this control, and the event parameter will contain EventArgs.Empty. The delegate can also be an instance of MethodInvoker, or any other delegate that takes a void parameter list. … Read more

How to call a method stored in a HashMap? (Java) [duplicate]

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With Java 8+ and Lambda expressions With lambdas (available in Java 8+) we can do it as follows: class Test { public static void main(String[] args) throws Exception { Map<Character, Runnable> commands = new HashMap<>(); // Populate commands map commands.put(‘h’, () -> System.out.println(“Help”)); commands.put(‘t’, () -> System.out.println(“Teleport”)); // Invoke some command char cmd = ‘t’; … Read more

How to execute a method passed as parameter to function

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You can just call it as a normal function: function myfunction(param1, callbackfunction) { //do processing here callbackfunction(); } The only extra thing is to mention context. If you want to be able to use the this keyword within your callback, you’ll have to assign it. This is frequently desirable behaviour. For instance: function myfunction(param1, callbackfunction) … Read more

How to use Reflection to Invoke an Overloaded Method in .NET

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You have to specify which method you want: class SomeType { void Foo(int size, string bar) { } void Foo() { } } SomeType obj = new SomeType(); // call with int and string arguments obj.GetType() .GetMethod(“Foo”, new Type[] { typeof(int), typeof(string) }) .Invoke(obj, new object[] { 42, “Hello” }); // call without arguments obj.GetType() … Read more

Invoke(Delegate)

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The answer to this question lies in how C# Controls work Controls in Windows Forms are bound to a specific thread and are not thread safe. Therefore, if you are calling a control’s method from a different thread, you must use one of the control’s invoke methods to marshal the call to the proper thread. … Read more

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