C# – Equivalent of typedef in C#

ctypedef

Is there a typedef equivalent in C#, or someway to get some sort of similar behaviour? I've done some googling, but everywhere I look seems to be negative. Currently I have a situation similar to the following:

class GenericClass<T> 
{
    public event EventHandler<EventData> MyEvent;
    public class EventData : EventArgs { /* snip */ }
    // ... snip
}

Now, it doesn't take a rocket scientist to figure out that this can very quickly lead to a lot of typing (apologies for the horrible pun) when trying to implement a handler for that event. It'd end up being something like this:

GenericClass<int> gcInt = new GenericClass<int>;
gcInt.MyEvent += new EventHandler<GenericClass<int>.EventData>(gcInt_MyEvent);
// ...

private void gcInt_MyEvent(object sender, GenericClass<int>.EventData e)
{
    throw new NotImplementedException();
}

Except, in my case, I was already using a complex type, not just an int. It'd be nice if it were possible to simplify this a little…

Edit: ie. perhaps typedefing the EventHandler instead of needing to redefine it to get similar behaviour.

Best Answer

No, there's no true equivalent of typedef. You can use 'using' directives within one file, e.g.

using CustomerList = System.Collections.Generic.List<Customer>;

but that will only impact that source file. In C and C++, my experience is that typedef is usually used within .h files which are included widely - so a single typedef can be used over a whole project. That ability does not exist in C#, because there's no #include functionality in C# that would allow you to include the using directives from one file in another.

Fortunately, the example you give does have a fix - implicit method group conversion. You can change your event subscription line to just:

gcInt.MyEvent += gcInt_MyEvent;

:)

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