How Can I Transfer an Event Handler Between Controls in C#?

Can You Slyly "Steal" Event Handlers?

In a coding quandary, you seek to transfer an event handler from one control to another. Yet, the compiler stands as an unyielding barrier.

The Code Conundrum:

Button btn1 = new Button();
btn1.Click += new EventHandler(btn1_Click);
Button btn2 = new Button();
// Assign btn1's event to btn2 (but met with rejection from compiler)
btn2.Click += btn1.Click; // Compiler denies

Possible Theft Techniques:

• Direct Transfer: Alas, this seemingly straightforward approach triggers a stern compiler retort.
• Handler Replication: Copying the event handler and assigning it to multiple controls is doable. However, it's not the sought-after solution in this case.

The Reflection-Based Trick:

If brute force isn't your style, then donning the cloak of reflection may unveil a covert path.

using System.Reflection;

// Declare event key
FieldInfo eventClick = typeof(Control).GetField("EventClick", BindingFlags.NonPublic | BindingFlags.Static);

// Retrieve click event
PropertyInfo eventsProp = typeof(Component).GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance);

EventHandlerList events1 = (EventHandlerList)eventsProp.GetValue(btn1, null);
Delegate click = events1[eventClick.GetValue(null)];

// Remove from btn1, assign to btn2
events1.RemoveHandler(eventClick.GetValue(null), click);
EventHandlerList events2 = (EventHandlerList)eventsProp.GetValue(btn2, null);
events2.AddHandler(eventClick.GetValue(null), click);

Beware, Microsoft has erected formidable barriers to prevent such maneuvers. But for those who dare, this reflection-wielding technique grants access to hidden realms of event handling!

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