Re: [wxhaskell-devel] Debugging wxHaskell with ghci - Windows issue

[Brian L. <br...@lo...>]

On Wednesday, 18.11.09 at 22:18, Jeremy O'Donoghue wrote:
> ...
> can't load .so/.DLL for: stdc++ (addDLL: could not load DLL)
>
> I notice that in the wxcore Setup.hs build file, you manually append
> stdc++ to the list of libraries reported by wx-config.

Yes, sorry about that. :(

> I don't think wxcore actually depends on libstdc++. wxWidgets does
> (unless you explicitly compile without it) for sure, and I assume that
> on Linux you therefore need the libstdc++ to make everything link. Is
> this correct?

I don't remember the exact error, but I remember that whatever it was
indicated a lack of libstdc++. I think it happened in Linux and OSX.

> I'm going to experiment with removing the libstdc++ dependency for
> Windows platforms, to see if this makes the problem go away. I'll keep
> you posted.

OK, thanks.

I worked on the "StartStart" (bugs/StartStart.hs) problem too. I didn't
really get anywhere.

Graphics/UI/WX.hs 'start' calls 'run'.
Graphics/UI/WXCore.hs 'run' calls 'appOnInit'.
Graphics/UI/WXCore/Events.hs 'appOnInit' calls 'wxcAppInitializeC'.
Graphics/UI/WXCore/WxcClassesMZ.hz 'wxcAppInitializeC' calls
  'ELJApp_InitializeC'.
ewxw_main.cpp 'ELJApp_InitializeC' calls 'wxEntry'.

So like Conal said, calling 'start' twice ends up calling 'wxEntry'
twice. There are lots of threads on the net related to wxWidgets
segfaulting on the second call of 'wxEntry'. Most info I found seemed to
say we just shouldn't do that (or need to). [1] seems to say that we
should be able to reset stuff with 'wxApp::CleanUp', but I'm not sure
how to use it in ewxw_main.cpp; doesn't that notation mean the caller
has to be a subclass of wxApp or something?

However, the wxCL people seemed to think that calling 'wxEntry' twice
was necessary, and had provided patches [2] a long time ago. I don't
know what became of that. I'm asking on their dev list. FWIW, they use
an identical (if you disregard whitespace) ewxw_main.cpp.

1: http://trac.wxwidgets.org/ticket/994
2: http://trac.wxwidgets.org/ticket/3162