🚀 go-pugleaf

Ben Jones wrote:
> 
> Anders Lindback (alindbac@sw.seisy.abb.se) wrote:
> : In article <4gsi2p$905@bcarh8ab.bnr.ca>,
> : brian (b.c.) white <bcwhite@bnr.ca> wrote:
> : >
> : >>What is needed is the ability to use member functions as callbacks
> : >>without any constraint on the type of the object they are invoked on.
> : >>This is possible in C++ only by using various implementation-dependent
> : >>hacks to escape the type system, because the language does not provide
> : >>any way to express such a construct.
> : >
> 
> The point we have been making is that there is a trivial way to extend
> the C++ language to provide for completely typesafe callbacks which
> are simple to use and which will dramatically improve the clarity
> of programs.
> 

I don't seem to understand the discussion in this thread.  Yet it seems to generate 
some strong opinions.  So, . . . 

The routine that will issue the callback (let us call it the driver) needs to use a
stored pointer.  The argument is that the stored pointer should be to a member function.  
Why isn't it good enough for the stored pointer to be a pointer to the object and then 
the driver will only need to say "object->callback();" in order to call the proper routine.
The usual virtual function semantics would take care of any inheritance hierarchy.

If the driver could deal directly with the address of a non-static member function 
how would the "this" parameter be supplied by the caller?

The X example seems to be showing an inteface between a C environment and a C++
environment.  Is that the real problem?

Am I missing something here?

Shalom Reich


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