Re: [Swig-devel] typemaps won't work in constructor when there is more than 1 constructor

[Soeren S. <swi...@nn...>]

On Wed, 2008-04-16 at 10:40 +0200, Amaury Forgeot d'Arc wrote:
> Hello,
> 
> Soeren Sonnenburg wrote:
> > Dear all,
> >
> >  whenever more than a single C++ constructor is defined, typemaps will
> >  not be applied for the constructor.
> >
> >  I've finally managed to isolate the problem (minimal example attached).
> >
> >  For example lets extend the class python example to have
> >
> >   Square(double w) : width(w) { };
> >
> >   Square(double d[3]) {
> >       x=d[0];
> >       y=d[1];
> >       width=d[2];
> >   }
> >
> >   void set_defaults(double d[3]) {
> >       x=d[0];
> >       y=d[1];
> >       width=d[2];
> >   }
> >
> >  and add a typemap
> >
> >  %typemap(in) (double vals[3]) (double loc[3])
> >  {
> >   //do sth.
> >  }
> >
> >  %apply (double vals[3]) {double d[3]}
> >
> >
> >  Now this will work:
> >
> >  s=example.Square(10)
> >  s.set_defaults([1,2,3])
> >  print "    Square = (%f, %f) area=%f" % (s.x,s.y,s.area())
> >
> >  But not
> >
> >  s=example.Square([1,2,3])
> >  print "    Square = (%f, %f) area=%f" % (s.x,s.y,s.area())
> >
> >
> >  A fix is to
> >
> >  a) remove Square(double w);
> >  b) use %ignore Square(double w); in the .i file
> >
> >  So it seems the typemaps are applied before the constructor wrappers are
> >  unrolled. Note that this happens regardless of the interface (happens in
> >  python/octave/R...)
> >
> >  A toy example to trigger this is attached, just untar in the
> >  Examples/python directory (it will create a typemap directory), then
> >  cd typemap
> >  make
> >  python runme.py
> >
> >  Any ideas on how to fix this ?
> >  Soeren
> 
> From the Swig doc::
>     If you define new "in" typemaps *and* your program uses overloaded methods,
>     you should also define a collection of "typecheck" typemaps
> 
> I tried this, and your test case seems to work::
> 
>     %typemap(typecheck, precedence=SWIG_TYPECHECK_DOUBLE_ARRAY) (double vals[3])
>     {
>         $1 = PySequence_Check($input) && (PySequence_Size($input) == 3);
>     }

Yes indeed it works :-)) Looks like I have completely missed the
typecheck section 
http://www.swig.org/Doc1.3/Typemaps.html#Typemaps_overloading 
- but it is great news - you made my day!

> Note that in your sample, the content of the typemap is not even used,
> since the check for "double" has a higher priority as
> SWIG_TYPECHECK_DOUBLE_ARRAY. So I don't know if it is even correct ;-)

Looking at the table in the above link with the precedence list (*), as
I understand it, first POINTER types will be checked then  at some point
DOUBLE and much later DOUBLE_ARRAY, but still as the typechekc for
double/int must fail, it falls through to DOUBLE_ARRAY which succeeds
(and works - I added some test printf's!).

Thanks so much!
Soeren.

(*) seems like this is upward compatible as I am not aware of any INT128
type...