Re: [Swig-devel] Python overloading with bool

[William S F. <ws...@fu...>]

Nitro wrote:
> Am 05.07.2008, 22:36 Uhr, schrieb William S Fulton
> <ws...@fu...>:
>
> > I found a problem with the Python typemaps when bool is overloaded with
> > some other numeric types. It was impossible to call the bool overload. I
> > have an example class below and the fix supplying a typecheck typemap.
> > The original typecheck typemap relies on SWIG_AsVal_bool to indicate
> > whether the typemap can be converted to bool...
>
> I have seen this in my wrappers before, but never bothered to
> investigate the problem more deeply. Does this happen with and without
> the -castmode option (the casting rank mechanism) or just with one of 
> them?
>
I don't really know this option to be honest. It looks like it uses 
implicit conversions, so am not sure how it differs from %implicitconv. 
Anyway, I think it is doing the right thing. Here is a test case for the 
example I showed earlier...

from example import *

class Ai():
   def __init__(self,x):
      self.x = x
   def __int__(self):
      return self.x

x = XMLFile("hi", False)
x = XMLFile("hi", True)
x = XMLFile("hi", 0)
x = XMLFile("hi", 1)
x = XMLFile("hi", 2)
x = XMLFile("hi", 0.0)
x = XMLFile("hi", 1.0)
x = XMLFile("hi", 2.0)
x = XMLFile("hi", 2.2)

x = XMLFile("hi", Ai(4))

With the new typecheck typemap and -castmode, the output is:

XmlFile(string=hi, bool=0)
XmlFile(string=hi, bool=1)
XmlFile(string=hi, int=0)
XmlFile(string=hi, int=1)
XmlFile(string=hi, int=2)
XmlFile(string=hi, double=0)
XmlFile(string=hi, double=1)
XmlFile(string=hi, double=2)
XmlFile(string=hi, double=2.2)
XmlFile(string=hi, int=4)

Which seems sensible to me. There is a change in behaviour to previously 
though without -castmode. When calling just:

x = XMLFile("hi", Ai(4))

we got this output:

XmlFile(string=hi, bool=1)

which seems plain wrong to me. Now we get:

NotImplementedError: Wrong number of arguments for overloaded function 
'new_XMLFile'.
  Possible C/C++ prototypes are:
    XMLFile(std::string const &,bool)
    XMLFile(std::string const &)
    XMLFile(std::string const &,double)
    XMLFile(std::string const &,int)

Which seems better like the right thing to me.

Is there an equivalent to 'def __int__(self)' for converting to 
booleans? That might be worth testing.

William