Question

What will happen if I create an Extension method (EM) with same signature as a native method.

My Scenario

I created an Extension Method

public static class EM
{
    public static void ForEach<T>(this List<T> enu, Action<T> action)
    {            
        foreach (T item in enu)
            action(item);
    }
}

Now since List also has a function with same signature

public void ForEach(Action<T> action);

so for List I did

List<Label> re = new List<Label>();
re.ForEach(x => Foo(x));

This compiles and runs but it does not call my EM and instead calls its native method. I am sure it will not show that there are 2 overloads since for overloading there has to be some change in signtaure

Queries

Q1. Why is this happening?

Q2. If there were more parameters, then i could have changed parameter order and called it. But how do I make him call my EM with same number of parameters (This is a very simple Explaination of my problem. My EM could have been a complex one)?

Answer 1

C# will always call the method on the class instead of calling the extension method. I suggest adding something to the name of the method to distinguish it. I personally use Ex at the end because it is short and reminds me that it is an extension method.

public static class EM
{
    public static void ForEachEx<T>(this List<T> enu, Action<T> action)
    {            
        foreach (T item in enu)
            action(item);
    }
}