C# Delegate Event Registration: What's the Real Difference Between `[object].[event] = anEvent;` and `[object].[event] = new EventHandler(anEvent);`?

C# event registration: Subtle differences between = anEvent; and = new EventHandler(anEvent);

The event handling mechanism in C# is crucial for building reactive and interactive applications. One aspect of event handling involves registering event handlers to specific events. When it comes to delegated event registration, two syntaxes are common:

<code class="language-csharp">[object].[event] += anEvent;</code>

<code class="language-csharp">[object].[event] += new EventHandler(anEvent);</code>

Dive into the differences

At first, it was thought that the two grammars exhibited different behaviors. However, the latest update clarifies that both methods are functionally equivalent. The first syntax simply uses delegate inference to automatically determine the appropriate delegate type, while the second syntax explicitly specifies the EventHandler delegate.

Delegation inference in C# 2.0 and higher

Prior to C# 2.0, the second syntax was the only viable option for delegated event registration. However, with the introduction of delegate inference, C# 2.0 and later also allows the first syntax.

The role of the compiler

In the first example, the compiler infers that the delegate should be an EventHandler because this is the standard delegate type for events. This simplifies the syntax and reduces code redundancy.

Explicit delegate specification

In the second example, the EventHandler delegate is explicitly specified, which is useful in scenarios where clarity is required or where the delegate type may not be immediately inferred.

Syntactic convenience

While both syntaxes can achieve the same results, which one to choose mainly comes down to personal preference. For concise and readable code, the first syntax of delegate inference is usually preferred. For clarity and unambiguity, the second syntax can be used as needed.

Conclusion

In short, the obvious difference between these two delegate event registration syntaxes is just a matter of syntactic sugar. Both approaches ultimately produce the same functionality, giving developers the flexibility to choose the syntax that best suits their specific needs.

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