How Can I Pass Additional Parameters to Event Handlers in C#?

Pass additional parameters to the event handler

In event-driven programming, event handlers are typically assigned using methods that accept only the sender object as a parameter. However, sometimes you may need to pass additional data to the event handler.

Example:

Consider the following code:

<code class="language-csharp">private void setup(string someData)
{
     Object.assignHandler(evHandler);
}

public void evHandler(Object sender)
{
    // 需要在此处使用 someData!!!
}</code>

In this example, evHandler is an event handler and needs access to the someData string available in the setup method.

Solution:

To pass someData to evHandler, you can define an event handler using a lambda expression like this:

<code class="language-csharp">private void setup(string someData)
{
     Object.assignHandler((sender) => evHandler(sender, someData));
}
public void evHandler(Object sender, string someData)
{
    // 需要在此处使用 someData!!!
}</code>

In this code, the lambda expression (sender) => evHandler(sender, someData) creates a new event handler that takes the sender object as a parameter and passes it along with someData to the evHandler method. This ensures that someData is available in the event handler.

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