CODEWITHSUNDEEP
c#interface
JAX
JAX

Reputation: 1620

Implementing IEnumerable Interface

I know that IEnumerable is an interface, and I also know that when a class implements an interface it has to implement specific bodies for the methods in that interface. I've been writing a program recently and I felt that I need to implement the Ienumerable to one of my class so as to allow it to be used in a foreach loop. After I did so which is done this way:

class FData: IEnumerable<EClass> {

    // Removed the irrelevant contents
    public IEnumerator<EnumerableClass> GetEnumerator()
    {       
        for (int i = 0; i < Emp_Id.Count; i++) {
            yield return (new EnumerableClass { Emp_Id = Emp_Id[i], Salary = Salary[i] });
        }
    }
    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
        return this.GetEnumerator();
    }
}

I see that my FData class can be used exactly like a List as if it is inheriting all the enumerable methods such as Select(), All(), Any() ,etc.

I'd like to know how exactly does this happen if the behavior of these method are not defined in the interface ?

Upvotes: 0

Views: 103

Answers (2)

Jeremy Cook
Jeremy Cook

Reputation: 22153

They are extension methods and here's some more info.

Extension methods exist as static methods within static classes within some namespace and the first argument of the method includes the this keyword (see the example method signature below of OfType). In this case you are probably seeing the System.Linq.Enumerable extension methods. If you were to remove the using System.Linq namespace from your class file those extension methods would no longer be available. After market refactoring tools like Resharper will suggest extension methods where appropriate, but what you get out of the box in Visual Studio will not suggest extension methods (e.g. Ctrl+.). Therefore, if you want them you must make sure to add an appropriate using statement at the top of your class file. If you do not want them and do not need any other class in the namespace you can remove it and the extension methods will no longer be available.

public static IEnumerable<TResult> OfType<TResult>(this IEnumerable source);

The beauty of this is that anything that implements IEnumerable will have the OfType method available so long as the namespace of that extension method is included. You can also make your own extension methods.

Upvotes: 2

Christos
Christos

Reputation: 53958

All these methods are extension methods for types that implement the IEnumerable interface. So once a type implements IEnumerable has as methods also these methods - except the methods, that have been already defined inside the body of your type.

For further documentation, please have a look here. Also, if you haven't before heard about extension methods, please first have a look here.

Upvotes: 7

Related Questions