[geos-devel] c api questions for SWIG

[strk at refractions.net]

On Mon, Jul 10, 2006 at 03:13:28PM -0600, Charlie Savage wrote:
> While I'm working through the SWIG bindings, I've come up with a few 
> questions/issues about the c api.
> 
> 1.  GEOSGeomTypeId.  This is both a method name in the CAPI and the name 
> of an enum.  This causes problems in the SWIG bindings because I have 
> code that does this:
> 
>     GEOSGeomTypeIdgeomId = (GEOSGeomTypeId)GEOSGeomTypeId(geom);
> 
>     switch (geomId)
>     {
>     case GEOS_POINT:
>     case GEOS_LINESTRING:
>     etc.
>     }
> 
> VC++ won't compile this code (haven't checked gcc).  However, it seems 
> like a bad idea to have the same identifier used for two different 
> things.  Can we change the name of the enum to something like GeomTypeID?

I already renamed the enum to GEOSGeomTypes.

> 2.  Message handlers have this signature:
> 
>    typedef void (*GEOSMessageHandler)(const char *fmt, ...);
> 
> Are the ... parameters ever used (I didn't see any place where they 
> were).  If they are used, what are they?  If not, should they be removed?

'...' is for variable args.
It's the same signature of printf from stdio.h.

I would not change this as it would break existing code.

BTW, you made me notice we're not using it correctly: an unlikely
exception containing any format string might crash the app...

> 3.  Init/Finish.  In SWIG I can automatically call initGEOS and install 
> the message handlers.  But I don't know of a way to call finishGEOS 
> automatically.  What happens if the SWIG bindings don't call it?

In HEAD finishGEOS() is a no-op. In 2.2 deletes a GeometryFactory.
At worst you'll leak.

--strk;