wxruby development - Nov 2006 - get_client_data

As a first stab at understanding swig''s mem mgmt features, I tried to 
fix get_client_data, using Wx::Choice as a testbed.

The attached patch resolves the immediate crasher with this function 
(which was b/c the typemap for void* isn''t right for this method). It 
also uses the %markfunc feature to prevent objects that are set as 
client data from being GC''d. The mini-script attached exercises both 
these issues.

It works for me, but there''s still a few issues:
1) Ideally we would implement this in ControlWithItems - but that''s an 
abstract class, and the methods are overridden in all the subclasses 
(like Choice). Is there a way round this?

2) Adding this seems to cause on segfault on exit/cleanup:
Program received signal EXC_BAD_ACCESS, Could not access memory.
0x00000000 in ?? ()

3) It gives some compile warnings about converting void* to VALUE - I 
understand the problem, but I don''t know C++ correct way to cast this.

Hopefully some of this can be useful elsewhere. TIA for your feedback.

alex



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Alex Fenton wrote:
> 2) Adding this seems to cause on segfault on exit/cleanup:
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> 0x00000000 in ?? ()
A quick update, cos I just discovered gdb''s ''whe''
command: it looks like
it''s segfaulting on exit because the mark function gets called, but the
underlying C++ Wx::Choice has already been freed. So when it calls 
GetCount, it accesses bad memory.

Anyone know how to check whether the pointer (to the Ruby obj) passed 
into wxChoice_mark still refers to a live C++ object?

alex