Optimize the numpy hook

[leogama]

As this is now called from Pickler.save(), which can be called from a dozen to thousands of times for a single "dump":

• Moved repeated logic to outside the numpy test functions
• Only create a save function once for each type
• Remove logic related to Python 2 old style classes
• Substituted black magic like comparing id(obj1.__bound_method__) == id(obj2.__bound_method__)* by type(obj1).__unbound_method__ is type(obj2).__unbound_method__)

(*) I was surprised that it worked at all, must be some kind of optimization but this is not described in the language.

Amend to #540

[leogama]

@mmckerns: The tests are failing because CLibraryLoaderType (ctypes.cdll of type ctypes.LibraryLoader) is registered as unpickleable for CPython < 3.11b3, but it pickles just fine. This class has __reduce__() and __reduce_ex__() methods implemented.

dill/dill/_objects.py

Lines 191 to 193 in bf0f4fa

	z = (sys.platform[:3] == 'win' or sys.platform[:6] == 'darwin') # non-'nux
	z = a if (sys.hexversion >= 0x30b00b3 and not z) else x
	z['CLibraryLoaderType'] = ctypes.cdll

But why on Earth are the tests of other PRs passing? Seems like a heisenbug... I see this same error on my machine.

[mmckerns]

Obviously, the types should just be registered the once, so yeah checking if they are in the dispatch table is the right thing to do. Thanks for the PR.

[mmckerns]

The tests are failing because CLibraryLoaderType (ctypes.cdll of type ctypes.LibraryLoader) is registered as unpickleable

It was failing due to getattr(cdll, 'mro', int.mro) throwing a OSError in the numpy* check functions. Fixed in: 43fd2ca

[leogama]

It was failing due to getattr(cdll, 'mro', int.mro) throwing a OSError in the numpy* check functions.

This doesn't make sense... The old versions of the numpy* functions were effectively calling getattr(cdll.__class__, 'mro', int.mro) (on the cdll class, not on the object). Furthermore, the lines that were generating the error are removed in this PR. So if the supposed failure to pickle cdll has anything to do with that functions, just the adjustment to _objects.py should be enough to solve the test error.

Note: on my machine, with all Python versions, cdll pickles just fine, so I can't track down this issue.

[mmckerns]

Note: on my machine, with all Python versions, cdll pickles just fine, so I can't track down this issue.

I have VMs for all supported platforms. The OSError didn't occur on linux, but did otherwise... so, yes, once that was adjusted for, then cdll pickled... and adjusting _objects.py enables the tests to pass.