[C++-sig] Pyplusplus: Support for anonymous structs?

Roman Yakovenko roman.yakovenko at gmail.com
Tue Jun 3 07:32:09 CEST 2008

On Mon, Jun 2, 2008 at 3:01 PM, Hans Meine
<meine at informatik.uni-hamburg.de> wrote:
> Hi Roman,
> after reporting to Gustavo that pybindgen does not support unnamed structs, I
> tried pyplusplus and found the same (OK, not the same - pyplusplus gracefully
> skips the members with the two warnings "Py++ can not export unnamed
> variables" and "Py++ can not export unnamed classes").  Actually, there are
> two problems:
> 1) py++ generates the following code, which does not mention the "low"
> and "high" members wrapped in the struct:
>    bp::class_< Word >( "Word" )
>        .def_readwrite( "word", &Word::word );
> This should be "easy to fix" - py++ would need to descend into the struct and
> add
>        .def_readwrite( "low", &Word::low )
>        .def_readwrite( "high", &Word::high )

py++ is not going support unnamed classes, unless someone will submit the patch.
Next code does the job (taken as-is from Python-Ogre project)

 def fix_unnamed_classes( classes, namespace ):
    for unnamed_cls in classes:
        named_parent = unnamed_cls.parent
        if not named_parent.name:
            named_parent = named_parent.parent
        if not named_parent or named_parent.ignore:
        for mvar in unnamed_cls.public_members:
            if not mvar.name:
            if mvar.ignore:
            if declarations.is_array (mvar.type):
                template = '''def_readonly("%(mvar)s",
                template = '''def_readwrite("%(mvar)s",
            named_parent.add_code( template % dict( ns=namespace,
mvar=mvar.name, parent=named_parent.name ) )

It takes list of unnamed classes.

> However, the next problem is fatal:
> 2) boost::python::class_ only works for structs and classes, but not for
> unions.  I am getting an error from is_polymorphic:

Thanks for bug reporting. I fixed this problem, by excluding unions
from being exposed :-)

Roman Yakovenko
C++ Python language binding

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