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

[Benjamin Ducke]

Go ahead and create all those interfaces if you like. Most people
I know, however, seem to be quite happy with C++ and Python.
Any language that does not have an open source implementation or
is not available for all QGIS-supported OS seems to be a waste of
time, though.

Ben

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
> 
> 
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> 
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-- 
Benjamin Ducke
Senior Applications Support and Development Officer

Oxford Archaeology Ltd
Janus House
Osney Mead
OX2 0ES
Oxford, U.K.

Tel: +44 (0)1865 263 800 (switchboard)
Tel: +44 (0)1865 980 758 (direct)
Fax :+44 (0)1865 793 496
benjamin.ducke at oxfordarch.co.uk




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