pygccxml-development

[pygccxml-development] Default values for pointers?

[Matthias B. <ba...@ir...>]

Hi,

this is probably a general Boost.Python question but anyway...

I have a couple of classes that have methods like the following:

   bool isDone(MStatus* ReturnStatus=NULL) const;

The MStatus object is just used for error reporting. When the user 
passes a MStatus object it will be filled with data specifying whether 
an error has occurred or not, but the user can also decide not to pass 
anything if he isn't interested in the error code.
pyplusplus generates the following code:

         MItDag_exposer.def( "isDone"
                 , &MItDag::isDone
                 , ( bp::arg("ReturnStatus")=0 )
                 , bp::default_call_policies() );

The module compiles fine, I can use it, but why isn't the argument not 
optional anymore? When I try to invoke the method without arguments I 
get an error by Boost.Python:

Boost.Python.ArgumentError: Python argument types in
     MItDag.isDone(MItDag)
did not match C++ signature:
     isDone(class MItDag {lvalue}, class MStatus * ReturnStatus=0)


Shouldn't the argument be optional as there is the "=0" in 
bp::arg("ReturnStatus")=0? Or should pyplusplus generate some other code?


- Matthias -

Re: [pygccxml-development] Default values for pointers?

[Roman Y. <rom...@gm...>]

On 3/22/06, Matthias Baas <ba...@ir...> wrote:
> Hi,
>
> this is probably a general Boost.Python question but anyway...
>
> I have a couple of classes that have methods like the following:
>
>    bool isDone(MStatus* ReturnStatus=3DNULL) const;
>
> The MStatus object is just used for error reporting. When the user
> passes a MStatus object it will be filled with data specifying whether
> an error has occurred or not, but the user can also decide not to pass
> anything if he isn't interested in the error code.
> pyplusplus generates the following code:
>
>          MItDag_exposer.def( "isDone"
>                  , &MItDag::isDone
>                  , ( bp::arg("ReturnStatus")=3D0 )
>                  , bp::default_call_policies() );
>
> The module compiles fine, I can use it, but why isn't the argument not
> optional anymore? When I try to invoke the method without arguments I
> get an error by Boost.Python:
>
> Boost.Python.ArgumentError: Python argument types in
>      MItDag.isDone(MItDag)
> did not match C++ signature:
>      isDone(class MItDag {lvalue}, class MStatus * ReturnStatus=3D0)
>
>
> Shouldn't the argument be optional as there is the "=3D0" in
> bp::arg("ReturnStatus")=3D0? Or should pyplusplus generate some other cod=
e?

1. I don't know
2. I will take a look what Pyste does
3. Can you try Google
4. boost.python - we always can ask for help there

> - Matthias -

Roman

--
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/

Re: [pygccxml-development] Default values for pointers?

[Roman Y. <rom...@gm...>]

Hi, Matthias, I think that this is your chance to try to understand
code creators.
This is really simple problem, after David Abrahams provided solution.

You need to take a look on code_creators/calldef.py file.

Good luck!

P.S.  I understand, that may be you don't have time for this task, so
I attach a file
with solution. You can replace your file with this one. I tested it.
Please place it in pyplusplus/code_creators directory. If you want,
you can commit it.
( I don't have time to learn command line args of cvs ).  Otherwise I
will commit it
and tester tomorrow.

thanks

--
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/