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C Sharp Delegates

Last updated Oct 31, 2022 Edit Source

# Delegates

delegates can help you write cleaner more modular and more functional code.

Delegates are defined as a function signature and return type but without any implementation.

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public delegate void TestDelegate();//returns void, takes no params

private TestDelegate testDelegateFunction;

private void Start() {
	testDelegateFunction = MyTestDelegateFunction;
	
	testDelegateFunction();
}

private void MyTestDelegateFunction() {
	Debug.Log("test");
}

Like events you need to subscribe delegates to functions. you can do this with =.

Make sure everything matches the right signature.

you can subscribe different functions to delegate with different behaviors, this can allow for nicely decoupled code.

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public delegate void TestDelegate();//returns void, takes no params

private TestDelegate testDelegateFunction;

private void Start() {
	testDelegateFunction = MyTestDelegateFunction;
	
	testDelegateFunction();
	
	testDelegateFunction = MySecondTestDelegateFunction;
	
	testDelegateFunction();
}

private void MyTestDelegateFunction() {
	Debug.Log("test");
}
private void MySecondTestDelegateFunction()
{
	Debug.Log("second test");
}

Delegates can also be multicast. Meaning multiple functions can be subscribed to one delegate. in this case us += for the later subscriptions.

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public delegate void TestDelegate();//returns void, takes no params

private TestDelegate testDelegateFunction;

private void Start() {
	testDelegateFunction = MyTestDelegateFunction;
	
	testDelegateFunction += MySecondTestDelegateFunction;
	
	testDelegateFunction();
}

private void MyTestDelegateFunction() {
	Debug.Log("test");
}
private void MySecondTestDelegateFunction()
{
	Debug.Log("second test");
}

just like events we can remove subscriptions with -=.

Delegates can have any return type and parameters.

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public delegate bool TestBoolDelegate(int i);

private TestBoolDelegate testBoolDelegateFunction;

private void Start()
{
	testBoolDelegateFunction = MyTestBoolDelegateFunction;
	Debug.Log(testBoolDelegateFunction(1));
}

private bool MyTestBoolDelegateFunction(int i){
	return i < 5;
}

!! when you define a delegate you need to give a name to the parameter, so just putting int won’t work. However, when you define a delegate function you don’t actually have to use the same name.

!! Under the hood: when we assign a delegate it’s actually doing this

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testDelegateFunction = new testDelegate(MyTestDelegateFunction);

# Anonymous Methods

Another way to create and assign delegates is through anonymous methods.

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testDelegateFunction = delegate () { Debug.Log("Anon Method") };

the anon needs to match the signature.

Another way is to use a Lambda expression.

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testDelegateFunction = () => { Debug.Log("lambda Method") };

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testBoolDelegateFunction = (int i) => { return i < 5; };

if you have a single statement then you can

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