Re: [pygccxml-development] Fwd: instance attribute with anonymous enum type

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

On Wed, Oct 15, 2008 at 7:06 PM, Gustavo Carneiro <gjc...@gm...> wrote:
> Sorry, Roman, I really meant to send to the mailing list! :-)

Hi. That's okey.

> From: Gustavo Carneiro <gjc...@gm...>
>
> Hello, I am hitting a problem in pygccxml regarding anonymous enums used as
> class member variables.
>
> Something like this:
>
> class SomeObject
> {
> public:
>
>     enum {
>         TYPE_FOO,
>         TYPE_BAR,
>     } type;
> };
>
> When I scan this, pygccxml tells me the attribute 'type' of 'SomeObject' is
> of type 'SomeObject'.  I happily try to generate code for this, and of
> course the generated code does not even compile:
>
> [14/25] cxx: build/default/tests/foomodule2.cc ->
> build/default/tests/foomodule2_9.o
> default/tests/foomodule2.cc: In function 'int
> _wrap_PySomeObject__set_type(PySomeObject*, PyObject*)':
> default/tests/foomodule2.cc:6211: error: cannot convert 'SomeObject' to
> 'SomeObject::<anonymous enum>' in assignment
> Build failed

Indeed, pygccxml has a problem to create full type name for unnamed
types, and the solution I choose, is to report named parts only.

> It would be better if pygccxml reported the type as  "SomeObject::<anonymous
> enum>", like GCC does.  This way at least I will not be lead me to generate
> invalid code (I prefer no code at all than erroneous code).

How? You still will have to check whether the type has name or not and
avoid the generation.

More over in this concrete example, you can do better. You can expose
all enum values as int within the class scope. Member variable "type"
could also be exposed as int.

Yes, this is a special case, but it could be completely handled by
code generator.

> This with pygccxml 0.9.5, gccxml 2008-04-20.
>
> My work around for the moment is:
>
>                 real_type = type_traits.remove_declarated(member.type)
>                 if hasattr(real_type, 'name') and not real_type.name:
>                     print >> sys.stderr, ">>>>>>>>>>>>>> skip anonymous
> type"
>                     continue

As I said unnamed types is a special case.

Py++ has solution for this and other issues. It extends every
declaration class, defined in pygccxml. One of the functions, it adds
is the ability of declarations to analyze "itself" and report
problems, and whether it could be exported or not.

For example:
http://pygccxml.svn.sourceforge.net/viewvc/pygccxml/pyplusplus_dev/pyplusplus/decl_wrappers/enumeration_wrapper.py?view=markup

http://pygccxml.svn.sourceforge.net/viewvc/pygccxml/pyplusplus_dev/pyplusplus/decl_wrappers/calldef_wrapper.py?revision=1428&view=markup

take a look on _exportable_impl method.

Thus the actual "code generator" code is clear, because it doesn't
need to deal with such cases. It just asks the declaration.

HTH

P.S. Hope I was clear. If not we can discuss it using IRC or gmail
chat. I have some free time now.

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