Call a method passed as parameter on an object passed as parameter

Question

I have a class defining several functions with the same signature

public class MyClass
{
    public string MyParam1() ...
    public string MyParam2() ...
    ...
}

From another class I want to call a method passed as parameter on an object passed as parameter

void MyFunction(MyClass anObject, Func<string> aMethod)
{
    string val = ??? // Here call aMethod on anObject
}

I'm pretty sure it's possible to do this using reflection, but is there a not to difficult way to do it ?

In fact I have a set of objects, not a single object, it's why I cannot call directly the method of the object.

Answer 1

If you pass the instance method as a function, it is already bound to the instance , so your anObject is useless in this case.

This code already operates on this :

MyFunction(null, this.DoSomething);

Here val will always be the result of this.DoSomething in the context of the caller:

string val = aMethod();

What you can do instead of passing the instance method around, is create a static method that has a parameter for anObject . In that way, your static method can do instance specific tasks.

public string MyParam2(MyClass instance) { }

void MyFunction(MyClass anObject, Func<MyClass, string> aMethod)
{
    string val = aMethod(anObject);
}

Answer 2

You don't need to worry about anObject as aMethod is already bound to an instance . The definition of a delegate is that it's a reference to an instance of a method .

Therefore the following should suffice:

void MyFunction(Func<string> aMethod)
{
    string val = aMethod();
}

Answer 3

If you really want to call a given method on a object, the don't use Func but pass in the object and the name of the method:

class Test
{
    public static void SayHello()
    {
        Console.WriteLine("Hello");
    }
}

void Main()
{
    var t = new Test();
    var methodInfo = t.GetType().GetMethod("SayHello");
    methodInfo.Invoke(t, null);

}

When executed, this will print

Hello

as it will call the SayHello method on the Test instance t .