Question

I didnt know how to word the question, so sorry if it doesnt really make sense, but it should start making sense here. Also, I am sorry if the solution is really, really simple. Google couldnt understand what I was asking (probs cause I was asking it wrong :P)

So I wrote a class that I called OrderSelection

In my program I need to have an array of OrderSelection objects, and I need to perform actions on this array (re-ordering, sorting etc).

What I am doing right now is keeping methods in the OrderSelection class that accept, among others, the array which you want to re-order, for example.

something like:

public void reorder(OrderSelection[] ord, int switchX, int switchY){....}

But What I want to be able to do is this:

OrderSelection[] order = new OrderSelection[10];
//do stuff
order.reorder(1,2);//which is WAY better than order[0].reorder(order, 1,2) as a horrid example

So yeah…how can I add these functions which I want to apply to an array of objects of my class?

thanks!

Answer 1

You’re looking for Extension Methods. Here’s the MSDN documentation.

Writing an extension method looks like this:

public static class OrderSelectionExtensionMethods
{
    public static void reorder(this OrderSelection[] orders, int x, int y) 
    {
        // Do something with each order
    }
}

Extension methods are usually defined in an entirely separate class.
Also, two things are required for Extension Methods:

• The entire class must be static
• The first parameter for each extension method must have the keyword this before it

With the above code, your example code would compile fine:

OrderSelection[] order = new OrderSelection[10];
//do stuff
order.reorder(1,2);

This is the exact same as writing the following:

OrderSelection[] order = new OrderSelection[10];
//do stuff
OrderSelectionExtensionMethods.reorder(order, 1, 2);