Re: [pygccxml-development] Py++ typedef handling

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

On Fri, Apr 24, 2009 at 2:03 AM, Patrick Hartling
<pat...@pr...> wrote:
>> I guess, it is possible to attach "pretty name" to a type and use it
>> for code generation, but this is a huge change.
>
> Is such an approach necessary, though? Since the type information identified
> by GCC-XML is the typedef, doesn't that mean that pygccxml or Py++ is
> "drilling down" to the un-aliased type in some cases?

Yes it does. And you know, may be you are right. May be it will be
enough to "fix" those places.

>>> What I see is that the typedef gets used in
>>> some places but not others. I haven't identified a pattern to this yet,
>>> but
>>> I am sure that there is one.
>>
>> Yes:
>> http://pygccxml.svn.sourceforge.net/viewvc/pygccxml/pyplusplus_dev/pyplusplus/decl_wrappers/decl_wrapper.py?revision=1664&view=markup
>>
>> Take a look on "_get_alias" method.
>
> I have used the alias property in some cases. Does it apply to what I
> posted, though? If so, then I am not seeing the full extent of what
> opportunities exist for operating on Py++ objects. For example, how can the
> alias property be used to alter the type casting done for keyword argument
> values?

I was thinking about using that alias, when I format function
arguments. For example:

#ifdef os64:
    typedef std::vector< int64 > numbers_t;
#else
    typedef std::vector< int32 > numbers_t;
#endif

void do_smth( numbers_t& );

I think, today, Py++ will generate do_smth with std::vector, which
contains int64 or int32. Finding out, that std::vector< int[32|64] >
class has alias and using it can improve the generated code.

Obviously, your patch produce the same result and it is much better
than my idea.

I need to check\verify my ideas before I raise them and may be to
sleep a little bit more :-)

>> It is very difficult. A year or two ago I tried to add something
>> similar to GCCXML ad got lost in GCC code. May be you will have more
>> luck.
>
> I cannot make any promises, and it depends on how my work hours are
> allocated. I would like to see this addressed, though, and maybe I can make
> a case for devoting time to it.

Good luck. GCC code is not the easiest code to read and understand.

>> Take a look on
>> http://pygccxml.svn.sourceforge.net/viewvc/pygccxml/pyplusplus_dev/examples/pyboost_dev/dev/date_time/generate_code.py?revision=1428&view=markup
>> file.
>> It contains code that does exactly this.
>>
>> Let me know if you need more help.
>
>
> That pointer is helpful. It set me on a course where I have already resolved
> several of our most frustrating issues.
>
> I have attached a small patch against the SVN trunk that makes a significant
> difference in generating more portable code--at least in our case. I have
> not yet run this change through the test suite (as I still have to learn how
> to run the test suite).

I committed the patch.

Thank you.

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