Hi Fabian,

On 12 May 2012 16:12, Fabian Binz <fabianb...@yahoo.de> wrote:

>   Hi Jeremy, ****
> I don't know if you continued working on this, but I forked wxHaskell on
> GitHub and tried to implement it myself:
> https://github.com/FabianBinz/wxHaskell
I have been doing some work, but I don't have a lot of time right now, so
it is going more slowly than I would like.

> For testing purposes, I only implemented the OnGetItemText and
> SetItemCount method and it seems to work.
> To implement the "virtual" list control, I defined a new class
> wxVirtualListCtrl in wxc:****
> https://github.com/FabianBinz/wxHaskell/blob/master/wxc/src/include/virtuallistctrl_impl.h
> ****
> Since it needs to invoke a callback function, I created the typedef
> OnGetItemTextCallback. To make wxdirect accept this new type, I extended
> the parser (patomtype) in ParseC.hs. This solution is very ad-hoc and I
> think because wxc is supposed to be a language agnostic C wrapper, we
> should maybe add another macro to wcx_types.hs (something like TCallback),
> which is then recognized by wxdirect.****
> So, while this all works pretty well, there is unfortunately a memory leak
> in Graphics.UI.WXCore.VirtualListCtrl, because of my use of newCString. At
> the moment I don't know how to fix it and would be glad if someone could
> give me some advice.

You need to use a finalizer - this is what I am looking into. There is an
overview at
but it could be clearer! Basic idea is that you free the CString when the
GC has no more references to the closure in which it is used.

I am using the event handler code as a model, since this already allows
callbacks from C to Haskell, and handles reference counting. Just haven't
finished yet.

I will take a look at your fork and see if you are further along than me,
and take code accordingly.

Best regards
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