Delegates vs. Events in C#: What's the Key Difference in Access Control?

Delegates and events in C#: the key difference is access control

Delegates and events are both mechanisms in C# that allow calling methods from one class to another. While they both share the common property of saving function references, there is a fundamental difference between the two:

Events provide encapsulation

An event declaration adds a layer of encapsulation around the delegate instance it encapsulates. This protection prevents external classes from modifying the delegate's invocation list (which contains references to methods to be executed).

Delegated to provide direct access

Delegates, on the other hand, have direct access to their invocation list. External classes can freely modify or replace methods in the delegate call list.

Event Mandatory Access Control

Events allow controlled access to their call list. Typically, subscribers to an event use the = or -= operators to add or remove methods from the invocation list. This prevents direct manipulation of the underlying delegate.

Delegation grants full control

A delegate grants unlimited access to its call list. Developers can directly manipulate the call list, adding or removing methods without any restrictions.

Summary

In summary, events provide a layer of protection around a delegate, limiting direct manipulation of it and ensuring controlled access to its invocation list. Delegates, on the other hand, allow full access to their invocation list, enabling flexible and dynamic method calls from external classes. Understanding these differences is critical to designing robust and scalable software systems.

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