🚀 go-pugleaf

In article <pauld.767898877@sarge>, pauld@verdix.com (Paul Durbin) writes:
|> I attempt to use a member function as callback but all three arguments (to the
|> callback) are garbage. If I make it a friend then the arguments are correct,
|> but then I can't get to the class data, without reference thru an instance of
|> the class and I don't want the data to be static.
|> 
|> So, what is causing this problem? Could I possibly use the *this pointer as
|> the client_data to the callback, then cast to the appropriate class?

The problem is that the first argument of any non-static member function in
C++ is the "this" pointer.  So if you try to register a member function
as a callback with (i.e. Motif), it won't work because Motif doesn't know
that the function it is calling is a member function and it will not pass
the "this" pointer.

Unfortunately, the only way around this problem (as far as I know) is to either
use the "this" pointer as the client_data (as you mentioned above) or write your
own mechanism for registering member functions as callbacks.

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