Delegates and Events (IT1811 Handout 1)

Vocabulary-style flashcards covering key terms from the lecture notes on Delegates and Events.

Delegate

A .NET class that encapsulates a method; a reference type that holds a reference to a method and can call methods with a matching signature.

Delegate signature

The return type and parameter list that must match the referenced method so the delegate can invoke it.

Declaring a delegate

Using the delegate keyword to declare a delegate in a class, specifying access modifier, return type, name, and parameters.

Instantiating a delegate

Creating a delegate instance using new or by assigning a method reference.

Invoking a delegate

Calling the method referenced by the delegate by invoking the delegate with appropriate arguments.

Generic delegate

A delegate not bound to a specific type, capable of referencing methods with different parameter and return types using a type parameter.

DisplayOutput

A generic delegate that takes a single parameter of type X and returns a value of type X.

Difference: delegates vs interfaces

Delegates are declarations with no implementation used as safe callbacks; interfaces declare methods that classes implement.

Event

A member of a class that fires when a specific action occurs and invokes its registered event handlers via delegates.

Event declaration

Declaring an event by declaring a delegate first, then using 'public event '.

Event subscription

Adding a handler to an event using the '+=' operator.

Event accessors

Compiler-generated add and remove methods for an event; can be customized with code in the accessors.

Add accessor

Code that runs when a new subscriber is added to an event.

Remove accessor

Code that runs when a subscriber is removed from an event.

Reference method

A method that is referenced by a delegate.

Parameter count matching

The delegate must have the same number of parameters as the referenced method.

Return type matching

The delegate's return type must match the referenced method's return type.

Static method reference

A static method can be referenced by a delegate.

Event handler

The method that is invoked in response to an event.