I wanted to know why use events and delegates when I can instead call functions normally?
Decoupling.
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Lets say you have a class called āButtonā. All it does is represent a simple button with text for a label and it can be clicked.
You add a button to your scene for the user to click. When the button is clicked, it calls a function called āStartGameā. And it loads the next scene. If you just call functions directlyā¦ it is now hardcoded to call āStartGameā.
Now, what if you add another button? And you label it āExit Gameā and you want it to call a function called āExitGameā which closes the application.
What do?
Copy the Button logic and make a āExitGameButtonā that calls āExitGameā when its clicked?
Thatāsā¦ a bit overkill.
Rather instead how about the Button have an event called āClickedā, and you can register a function with it to be called when the button gets clicked. Now you can reuse the same button code for multiple instances of buttons, but just like you can configure the label, you can also configure what function gets called.
ā¦
this is called ādecouplingā.
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More generally:
Why would you use variables like int x = 42 when you could just use the literal 42 everywhere you might have used x?
The answer is that variables give you generality. You can write block of code that can handle many different possible numbers, instead of only being able to handle 42. That way, if you discover tomorrow that you also need to handle 43, you donāt need to write new code for it.
You can even have the value of x change over the course of the program, so it means different things at different times.
Events and delegates are basically variables for functions. They allow you to write one block of code that can interact with a variety of different functions, instead of only with a single hard-coded function.
Is it all a performance thing?
Nothing in my post suggested it was a performance thing.
Itās a reduction of the amount of code you have to write. And instead designing systems abstractly. A button doesnāt do 1 thing (call 1 function), it can do many things, depending the situation.
The exit game button on the other hand does 1 thingā¦ but thatās a specific configured instance of A button.
It lets you treat a method itself as a variable. Very useful in certain situations.
I think, more important for everyone else to know is what issues you have or are facing when you use delegates and events to warrant this question at all.
delegates and events are so flexible in usage its hard to describe their advantages briefly. Youāll simply have to experience using them yourself in time.