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bpo-31581: Reduce the number of imports for functools #3757

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Merged
methane merged 7 commits into from
Sep 30, 2017
Merged

bpo-31581: Reduce the number of imports for functools #3757

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d648fc8
Reduce the number of imports for functools
methane Sep 26, 2017
f228a84
Revert collections module
methane Sep 26, 2017
cac0c73
Add comment about lazy import
methane Sep 26, 2017
865f333
Fix TestSingleDispatch
methane Sep 26, 2017
fd86dde
Use import instead of from ... import
methane Sep 27, 2017
26b0b32
Use support.swap_attr in TestSingleDispatch
methane Sep 27, 2017
99eeeb9
Add import comment at top of the module.
methane Sep 30, 2017
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Add comment about lazy import
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@methane
methane committed Sep 26, 2017
commit cac0c738cf7f45db4b43cea2afb431afad0dec6b
3 changes: 3 additions & 0 deletions Lib/functools.py
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Expand Up @@ -752,6 +752,9 @@ def singledispatch(func):
implementations can be registered using the register() attribute of the
generic function.
"""
# There are many programs that use functools without singledispatch, so we
# trade-off making singledispatch marginally slower for the benefit of
# making start-up of such applications slightly faster.
from types import MappingProxyType

@serhiy-storchaka serhiy-storchaka Sep 26, 2017

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It is slightly faster to import types and use types.MappingProxyType once than import MappingProxyType from types. The from ... import case runs a Python code from _bootstrap.py, while the former case runs just a C code if the types module already is imported.

from weakref import WeakKeyDictionary

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