[Qgis-developer] Some concerns about QGIS on OS X, part 3

[Tim Sutton]

Hi Phil

On Sunday 08 February 2009 04:51:37 Mac Programmer wrote:
> Many programmers, particularly new programmers, prefer to use LWOHF
> (languages without header files). I'm thinking here of the .NET
> languages C#, VB.NET and Delphi Prism (nee Oxygene) or Object Pascal
> as implemented in Delphi and Free Pascal. Currently QGIS only
> provides two extremes for adding value, C++ and Python. If this were
> 1999, in the heyday of desktop development, perhaps these traditional
> languages would make sense. But if we're living in 2009, or planning
> for, say, 2011, it would seem as though also having choices somewhere
> in the middle of the language spectrum would help QGIS adoption.
>
> What about proceduralizing the QGIS API similar to the way Den Jean
> has proceduralized much of the Qt API?
>
> http://users.telenet.be/Jan.Van.hijfte/qtforfpc/fpcqt4.html
>
> This would open up QGIS to most languages that can import C libraries.
>
> In my experience, C++ in the hands of even good programmers often
> results in unstable, fragile, difficult-to-maintain code, whereas
> Python is, well, a scripting language. Certainly Python has its uses
> and fTools and the Plugin Installer are excellent examples of how far
> you can take Python. But there are also many cases where Python is
> not appropriate and a compiled language is needed. (cf. the
> performance issues of the Python "Sugar" front-end and Python
> "activities" (apps) on the One Laptop Per Child (OLPC) computers.)
>
> Following Den's lead, an interface library written in C++ that
> flattens the QGIS API might look like this:
>
> #include <qgsapplication.h>
> #include "qgsapplication.hb"
>
> QgsApplicationH QgsApplication_create(int* argc, char** argv, int p3)
> {
> 	return (QgsApplicationH) new QgsApplication(*(int*)argc, argv, p3);
> }
>
> void QgsApplication_destroy(QgsApplicationH handle)
> {
> 	delete (QgsApplication *)handle;
> }
>
> int QgsApplication_exec()
> {
> 	return (int) QgsApplication::exec();
> }
>
> In Pascal, this library's functions can be imported like this:
>
> function QgsApplication_create(argc: PInteger; argv: PPAnsiChar; p3:
> Integer = QT_VERSION): QgsApplicationH; overload; cdecl; external
> QgisIntf name 'QgsApplication_create';
> procedure QgsApplication_destroy(handle: QgsApplicationH); cdecl;
> external QgisIntf name 'QgsApplication_destroy';
> function QgsApplication_exec(): Integer; cdecl; external QgisIntf
> name 'QgsApplication_exec';
>
> I've already tested this and it does work on OS X. I would follow up
> with more of this interface library, but I'm not sure I'm qualified -
> I'm not much of a C++ programmer, I have no GIS background, and I
> have no understanding of QGIS's architecture. Maybe there's somebody
> less error prone in this area who would be interested.
>
> Again, the objective here is to make adding value to QGIS as painless
> as possible.
>
> Thanks.
>
> -Phil

I think your idea is interesting but would add a level of complexity to the 
QGIS project that we are not equipped to handle at this time. Our developer 
team is small and in most cases volunteer only, so for me it doesnt make sense 
to embark an additional major maintenance commitment at this stage.

Regards

Tim

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