[Cython] Speedup module-level lookup

[Chris Colbert]

If it doesn't pass PyDict_CheckExact you won't be able to use it as the
globals to eval or exec. That's assuming you hack the module type so you
can change its __dict__.
On Jan 19, 2012 2:01 AM, "Robert Bradshaw" <robertwb at math.washington.edu>
wrote:

> On Wed, Jan 18, 2012 at 11:53 PM, Vitja Makarov <vitja.makarov at gmail.com>
> wrote:
> > 2012/1/19 Vitja Makarov <vitja.makarov at gmail.com>:
> >> 2012/1/19 Robert Bradshaw <robertwb at math.washington.edu>:
> >>> I think the right thing to do here is make all module-level globals
> >>> into "cdef public" attributes, i.e. C globals with getters and setters
> >>> for Python space. I'm not sure whether this would best be done by
> >>> creating a custom dict or module subclass, but it would probably be
> >>> cleaner and afford much more than a 1.6x speedup.
> >>>
> >>> - Robert
> >>>
> >>> On Wed, Jan 18, 2012 at 12:30 PM, Vitja Makarov <
> vitja.makarov at gmail.com> wrote:
> >>>> I tried to optimize module lookups (__pyx_m) by caching internal
> PyDict state.
> >>>>
> >>>> In this example bar() is 1.6 time faster (500us against 842us):
> >>>>
> >>>> C = 123
> >>>> def foo(a):
> >>>>     return C * adef bar():
> >>>>     for i in range(10000):        foo(i)
> >>>> Here is proof of
> >>>> concept:
> https://github.com/vitek/cython/commit/1d134fe54a74e6fc6d39d09973db499680b2a8d9
> >>>>
> >>>> So the question is: does it worth it?
> >>>>
> >>
> >> Yes, nice idea.
> >> It's possible to subclass PyModuleObject and I didn't find any use of
> >> PyModule_CheckExact() in CPython's sources:
> >>
> >> import types
> >> import sys
> >>
> >> global_foo = 1234
> >>
> >> class CustomModule(types.ModuleType):
> >>    def __init__(self, name):
> >>        types.ModuleType.__init__(self, name)
> >>        sys.modules[name] = self
> >>
> >>    @property
> >>    def foo(self):
> >>        return global_foo
> >>
> >>    @foo.setter
> >>    def foo(self, value):
> >>        global global_foo
> >>        global_foo = value
> >>
> >> CustomModule('foo')
> >>
> >> import foo
> >> print foo.foo
> >>
> >
> > But this seems to break globals().
>
> How so? We have to hack globals() to get it to work for a Cython
> module anyways. (I wonder if this must return a dict, or would any
> mapping (or subclass of dict) be sufficient...)
>
> - Robert
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