[issue25147] Enum: remove dependency on OrderedDict

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

_collections exists because it contains C implementations of some collections classes or helpers. _collections itself is imported only in collections and threading. And in threading the same idiom as proposed by Eric is used:

try:
    from _collections import deque as _deque
except ImportError:
    from collections import deque as _deque

What is the cost of importing OrderedDict at all? Ethan, can you provide any measurement results?

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nosy: +rhettinger

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<http://bugs.python.org/issue25147>
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