Can't figure out this issue with Generics

[Steve K.]

I am in over my head I think, I've got my brain running in circles trying to
figure this out.

I'm using remoting with a client and a server. I need the server to raise
events on the client and after doing quite a bit of reading I found what I
think is the correct way. The article I read encourages shims to pass the
delegate to server and back so that the client process doesn't need to be
passed. I barely understand it, I will understand more when I get it
working.

Anyway, these "Shim" classes in the example were tied to a specific delegate
and I wanted to create something a little more generic and reusable.

Here is the code I'm having trouble with:
<code>
// From the client
EventShimWithArgs<int[]>.Create(new
EventHandler<EventArgs<int[]>>(OnSomething));

// EventArgs <T>
public class EventArgs<T> : EventArgs
{
private T _data;

public EventArgs(T data)
{
_data = data;
}

public T Data
{
get { return _data; }
}
}



// On the server
public class EventShimWithArgs<T> : MarshalByRefObject
{
private EventHandler<EventArgs<T>> target;

private EventShimWithArgs(EventHandler<EventArgs<T>> target)
{
this.target += target;
}

public void Rar<T>(object sender, EventArgs<T> eventArgs)
{
target(this, eventArgs);
}

public static EventHandler<EventArgs<T>>
Create<T>(EventHandler<EventArgs<T>> target)
{
EventShimWithArgs<T> shim = new EventShimWithArgs<T>(target);
return new EventHandler<EventArgs<T>>( shim.Rar<T> );
}
}
</code>

The line that is giving me my last compiler error is:
target(this, eventArgs);

The error is:
<error>
cannot convert from

'PMD.OfficeStudio.Infrastructure.Interface.EventArgs<T>
[c:\PMDRepository\Tools\OfficeStudio\Source\Infrastructure\Infrastructure.Interface\bin\Debug\Infrastructure.Interface.dll]'

to

'PMD.OfficeStudio.Infrastructure.Interface.EventArgs<T>
[c:\PMDRepository\Tools\OfficeStudio\Source\Infrastructure\Infrastructure.Interface\bin\Debug\Infrastructure.Interface.dll]'

C:\PMDRepository\Tools\OfficeStudio\Server\OfficeStudioServerInterfaces\EventShimWithArgs.cs
OfficeStudioServer.Interface 23 26
</error>

Now... it's complaining about not being able to convert by the types it says
it can't covert are the SAME!

I'm stumped, anyone see the problem?

Thanks for any help!
Steve

 

[Marc Gravell]

the types it says it can't covert are the SAME!

I'm stumped, anyone see the problem?

Different T... errors are one thing, but also look at the *warnings*:
Warning 1 Type parameter 'T' has the same name as the type parameter
from outer type 'EventShimWithArgs<T>' d:\dump\wf
\ConsoleApplication2\ConsoleApplication2\Program.cs 60 21
ConsoleApplication2
Warning 2 Type parameter 'T' has the same name as the type parameter
from outer type 'EventShimWithArgs<T>' d:\dump\wf
\ConsoleApplication2\ConsoleApplication2\Program.cs 67 8
ConsoleApplication2

So:
Rar<T> and Create<T> should perhaps not be generic methods, but just
members of the generic class?
i.e. Rar(object sender, EventArgs<T> eventArgs) etc

If you *need* them as generic methods inside the generic class, then
pick a different name for the arg, i.e.
i.e. Rar<TSomethingElse>(...)
(pick a meaningful name...)

Marc

 

[sklett]

Hi Marc,

Great help, thanks so much. The warnings held the key! I've also modifed
the design per your suggestions and it seems to be working nicely now and I
learned something, always a good thing.

Take care,
Steve