generic newbie: returning TYPE from a method

[sklett]

I'd like to create a method like this:
private T FindCustomField<T>(string fieldID)
{

}

the compiler doesn't like that very much, I'm not sure if it's even possible
to use a Type parameter as the return type. Anyone know?

Thanks,
Steve

 

[sklett]

ah, looks like it is possible, I had a typo. Sorry for the false alarm.
Now I just need to learn how to tell the method that T is a class so I can
use the 'as' operator to cast a base class down to a T type.

 

[Lee Crabtree]

You can use a type constraint on generic classes to make sure the type
given is a class. I'm not sure about generic methods.

public class Thing<T> where T new()
{
}

DC

 

[Jon Skeet [C# MVP]]

ah, looks like it is possible, I had a typo. Sorry for the false alarm.
Now I just need to learn how to tell the method that T is a class so I can
use the 'as' operator to cast a base class down to a T type.

private T FindCustomField<T>(string fieldID) where T : class

Jon

 

[Nicholas Paldino [.NET/C# MVP]]

You can apply the constraint on the method just like you can on the
class:

private T FindCustomField<T>(string fieldID) where T : class
{

}

Also, to Lee, it should be noted that placing the new() constraint on
the type parameter will not guarantee that it only uses a reference type.
The new() constraint only limits the type to types that have a parameterless
constructor.

 

[sklett]

Thank you all for the help! :0)

I found the MSDN docs on constraints and it makes sense now.