Re: [Pyobjc-dev] NSDocument based app

[Jack J. <Jac...@cw...>]

On Wednesday, Nov 6, 2002, at 11:19 Europe/Amsterdam, Ronald Oussoren 
wrote:
>> So (void *) arguments are broken? Hmm... well I can avoid that in my 
>> example app by using the print panel rather than the sheet. The panel 
>> doesn't require a call back. There are a few things that use the 
>> (void *)contextInfo paradigm though, so we should probably fix it. 
>> What's the current scheme?
>>
> Not really broken, just not working as you want :-) Problem is that it 
> hard to automaticly translate from a Python object to a void*: Do you 
> want to pass the object itself (like you probably want to do here) or 
> should the object be translated to some native type (like you'd want 
> to do with 'int write(int fd, void* buf, int len)').
>
> The current scheme is that you'll have to manually write methods that 
> do the right thing. But, I'll probably add a mechanism to get this 
> type of void* arguments to work without writing C code.

What I tend to do if I run into this situation when wrapping an API is 
the following:
- If the Python object is None I pass NULL, else
- If the Python object conforms to the buffer protocol we use 
bf_getreadbuffer() or bf_getwritebuffer(), else
- if it's a PyCObject we use PyCObject_AsVoidPtr().
--
- Jack Jansen        <Jac...@or...>        
http://www.cwi.nl/~jack -
- If I can't dance I don't want to be part of your revolution -- Emma 
Goldman -