[PyKDE] Sip support for FILE */PyFileObject

[Phil Thompson]

On Tuesday 11 October 2005 4:17 pm, Nigel Stewart wrote:
> >>Another thing we've tried is creating a binding
> >>for struct FILE, but the sip-generated code
> >>is inclined to delete it once passed to
> >>MyWriter...
> >>
> >>struct FILE
> >>{
> >>%TypeHeaderCode
> >>#include <cstdio>
> >>using namespace std;
> >>%End
> >>
> >>private:
> >>     FILE();
> >>     FILE(const FILE &);
> >>     ~FILE();
> >>
> >>%ConvertToTypeCode
> >>
> >>     if (sipIsErr == NULL)
> >>         return PyFile_Check(sipPy);
> >>
> >>     if (PyFile_Check(sipPy))
> >>     {
> >>        *sipCppPtr = PyFile_AsFile(sipPy);
> >>        return 1;
> >>     }
> >>
> >>     *sipIsErr = 1;
> >>     return 0;
> >>%End
> >>};
> >
> > I don't know what you mean by "inclined to delete it". It should follow
> > the normal garbage collection rules. If you want MyWriter to take
> > ownership of the FILE then take ownership of it in the ctor.
>
>     Sorry for being vague.  %ConvertToTypeCode normally allocates a new
>     object - but in this special case it's merely unwrapping the existing
>     FILE pointer from the PyFileObject.
>
> (1)
>
> MyWriter(FILE *)
>
> ...
> 			if (a0IsTemp)
> 				delete a0;
>
> ...
>
>
> (2)
>
> MyWriter(FILE * /Transfer/)
>
> ...
> 			if (a0IsTemp)
> 				delete a0;
> ...
>
>
>      There seems to be an assumption that %ConvertToTypeCode creates
>      a copy that needs to be deleted and ownership can't be transferred
>      to C++.

It's not an assumption - it's the return value of %ConvertToTypeCode. Just 
make sure it always returns 0.

Phil