Adding a function as an object's property

Question

In my project I'm implementing an action class and was wondering if it was possible to pass a function as a parameter like this:

public class Action : MonoBehavior {
  public int ID;
  public string Name;
  //Test variable to store a function here
}

Where later I would create a function, such as this one, and call it.

void TestFunction() {
  print("Test");
}
public Action ExampleAction;
ExampleAction.Test = TestFunction();

And then finally I could simply call "Action.Test" to run TestFunction.

I've done some research on the topic and I believe it's somewhat related to delegation but how could I do it in this scenario?

And even more, is this sort of implementation reliable or the nicest way to do it? In my project I plan on having a lot of toggleable actions, that when clicked, will continuously do a large variety of different things.

You can store delegates. Define the function signature and then you can just directly assign it. Then calling it can be done by referencing the stored delegate. `public void YourDelegate(parameters);`. Then save a reference of it `private YourDelegate = null`. Then assign it with a function of the same signature (scope, return type and parameters). — TEEBQNE, Sep 23 '21 at 17:48
In your case it would simply be [`public System.Action Test;`](https://learn.microsoft.com/dotnet/api/system.action) — derHugo, Sep 23 '21 at 18:32
Also related btw [Pass method as parameter using c#](https://stackoverflow.com/questions/2082615/pass-method-as-parameter-using-c-sharp) -> between "pass" and "store" there is little difference ;) — derHugo, Sep 24 '21 at 04:31

score 1 · Accepted Answer · answered Sep 23 '21 at 20:07

To my understanding, what you are trying to do is create a parameterized delegate.

I think UnityAction fit this perfectly. UnityAction is a built-in delegate that takes no parameters and returns no value.

In your case, you would want to use a parameterized UnityAction<T1, T2>, where you would set T1 to int and T2 to string.

Here is a snippet for demonstration:

using UnityEngine;
using UnityEngine.Events;

public class UnityActionDemo
{
    UnityAction<int, string> action;
    private void Start()
    {
        action = TestMethod;
    }

    public void TestMethod(int id, string name)
    {
        Debug.Log("id is: " + id + "\t name is: " + name);
    }
}

action can then be passed around to any method that takes a UnityAction<int, string> as a parameter.

In order to invoke the method, call action.Invoke with the parameters you'd like to use:

action.Invoke(27, "A cool method name");

:)

Never understood the purpose of `UnityAction` to be honest ... There already is `System.Action` which does exactly the same ... So either it does some additional stuff or is pretty much redundant — derHugo, Sep 24 '21 at 04:28
I'm not sure about it myself. Maybe the internal implementations are more optimized to how Unity works? Just shooting in the dark. — Guy Michael, Sep 28 '21 at 11:31

Adding a function as an object's property

1 Answers1