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Popularfan
Asked: 2022-03-17 04:17:24 +0800 CST 2022-03-17 04:17:24 +0800 CST

C# How to save a method in a variable to be called later?

  • 772

I have the following method in a C# class

void Mimetodo(string parametro1, string parametro2)
{
   // Código del metodo
}

void Mimetodo2(int parametro1)
{
   // Código del metodo
}

and now what I want is to match that method to a variable to make a call later, for example something like this:

va = Mimetodo("5", "4");
vb = Mimetodo2(3);
if (opcion == "1") v = vb;
if (opcion == "2") v = va;
v; // Esto seria una llamada a la función que toca.

That is, I want to save the reference to the call of that function.

c#

2 Answers

  1. Best Answer

    One option is to use the Action delegate , which allows you to wrap a method.

    Action<string, string> funcion = MimeTodo;
            
funcion("hola", "mundo"); // Esta es la llamada a la función MimeTodo con los parámetros especificados

    However, you will still need to pass parameters to the Action instance.

    To avoid this, we can use a lambda expression.

    Action funcion = () => MimeTodo("hola", "mundo");

funcion(); // Esta es la llamada a la función lambda, que a su vez ejecuta el método MimeTodo
    • 5

  2. Previous note: I had added this answer without realizing that @JhonRM had already provided the correct answer. I was about to delete it when I saw it, but I'm going to leave it because here I also explain a bit about the use of Funcas opposed to Action, which I think may be useful to a future user with a similar question. Please do not vote positively, the correct answer was already given by JhonRM and he deserves the positive votes.

    This is an interesting question. In older versions of the compiler, you could do it using delegates , but the language has long had something that might fit what you're asking for: ActionyFunc

    According to the documentation:

    Action encapsulates a method that has no parameters and does not return a value.

    and about Func(there are several signatures, this would be a general definition):

    Wraps a method and returns a value of the type specified by the TResult parameter.

    Combining these delegates with lambdas, it's relatively easy to get what you want. I'll give you an example with both:

    static string Mimetodo(string parametro1, string parametro2)
{
    return parametro1 + " "+ parametro2;
}

static void Mimetodo2(string parametro1, string parametro2)
{
    Console.WriteLine(parametro1 + " "+ parametro2);
}

    Here we define two methods, one with a return value and the other with type void. Now we are going to see how we would store a call to each of them, and how we would finally call them:

    Func<string> variable = () => Mimetodo("a", "b");
Action variable2 = () => Mimetodo2("a","b");
    
if (opcion == "1") Console.WriteLine(variable());
if (opcion == "1") variable2();

    I hope this little explanation has been clear to you.

    • 4