Re: [pygccxml-development] Another performance tweak

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

On 8/26/06, Allen Bierbaum <al...@vr...> wrote:
> I just found some more tweaks.

Cool. I just committed a set of changes that will allow us to keep under control
cache results of different algorithms. I still have to write unit tests. These
changes allow you to continue grate work. Please take a look on them, what
do you think?

> - Caching the results of type_traits.remove_alias improved performance
> by 20%

Yes, this algorithms is used every where. Please don't commit this
change, I'd like
to think about it. I see next problem here: there are a lot of types,
so the cache
memory size could go out of control. Can you find out how many memory
Py++ takes with\without the cache?

> - (danger) Having create_identifier just return the exact same string
> passed as full_name improved performance another 20%.
>
> This last one was interesting because what I found was that (at least in
> my project) create_identifier was called about 16,000 times and it
> always returned the same value passed in.  This could be just because of
> how my project works (no namespace aliases that I know of) and is
> probably not portable.
>
> But, one very strange thing is why is this method being called for names
> like "boost::python::arg" and "boost::python::default_call_policies"?
> As far as I understand how py++ is working, these symbols are always
> going to be valid.  So why waste the time calling an expensive method if
> we already know the outcome?

:-) It seems that you missed the point. Py++ has few cool features.

mb = module_builder_t( ... )
mb.build_code_creator(...)
mb.code_creator.add_namespace_alias( "bpl", "::boost::python" )
or
mb.code_creator.add_namespace_usage( "::boost::python" )

See what happens.

The short version is that you can add to the code creators tree the namespace
usage and aliase and Py++ will generate code that takes into account them.

create_identfier function is responsible for creating such identifier.

It is safe to add such optimization, but similar work should be done.

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