methodinfo

How to get return Value from method invocation using reflection in C# and VB.NET

 

To get return Value from method invocation using reflection in C# and VB.NET you can use the snippet below.

Sample C#

var returnValue = (Int32)methodInfo.Invoke(null,null); //just cast the returned object of Invoke to the needed Type. Theres no difference if it is a static method/class or not

Sample VB.NET

Dim returnValue = DirectCast(methodInfo.Invoke(Nothing, Nothing), Int32) 'just cast the returned object of Invoke to the needed Type. Theres no difference if it is a static method/class or not

For more informations on how to invoke methods from other assemblies using reflection see:

  • How to call a static method in different assembly using Reflection in C# and VB.NET
  • How to call a non-static method in different assembly using Reflection in C# and VB.NET

    • Dynamic Event Subscription using C# or VB.NET

     

    The following snippet let you dynamically subscribe to events using C# or VB.NET.

    Sample C#

    //usage DynamicEventSubscription("button1", "Click", "button1_Click");
public void DynamicEventSubscription(string controlName,string eventName, string targetName, bool recursiveSearch=false)
{
	if (controlName == String.Empty) { throw new ArgumentNullException("controlName"); }
	if (eventName == String.Empty) { throw new ArgumentNullException("eventName"); }
	if (targetName == String.Empty) { throw new ArgumentNullException("targetName"); }

	try
	{
		var eventMethod = GetType().GetMethod(targetName);
		var control = Controls.Find(controlName, false).FirstOrDefault();
		if (control != null)
		{
			var eventToSubscribe = control.GetType().GetEvent(eventName);
			var handler = Delegate.CreateDelegate(eventToSubscribe.EventHandlerType, this, eventMethod);
			var button = Controls.Find(controlName, recursiveSearch).FirstOrDefault();
			eventToSubscribe.AddEventHandler(button, handler);
		}
	}
	catch (Exception ex)
	{
		//handle the exception your way
	}
}

    Sample VB.NET

    'usage DynamicEventSubscription("button1", "Click", "button1_Click")
Public Sub DynamicEventSubscription(controlName As String, eventName As String, targetName As String, Optional recursiveSearch As Boolean = False)
	If controlName = [String].Empty Then
		Throw New ArgumentNullException("controlName")
	End If
	If eventName = [String].Empty Then
		Throw New ArgumentNullException("eventName")
	End If
	If targetName = [String].Empty Then
		Throw New ArgumentNullException("targetName")
	End If

	Try
		Dim eventMethod = [GetType]().GetMethod(targetName)
		Dim control = Controls.Find(controlName, False).FirstOrDefault()
		If control IsNot Nothing Then
			Dim eventToSubscribe = control.[GetType]().GetEvent(eventName)
			Dim handler = [Delegate].CreateDelegate(eventToSubscribe.EventHandlerType, Me, eventMethod)
			Dim button = Controls.Find(controlName, recursiveSearch).FirstOrDefault()
			eventToSubscribe.AddEventHandler(button, handler)
		End If
			'handle the exception your way
	Catch ex As Exception
	End Try
End Sub

    In order to make this snippet work, you need to ensure that the target method is accessible via reflection. If you use .net 3.5 or lower, remove the optional parameter from the method signature.

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