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Support enum iteration #1136

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Merged
merged 2 commits into from
Apr 4, 2017
Merged

Support enum iteration #1136

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78d9f8e
Support enum iteration.
Feb 8, 2017
abfa7ac
Make EnumMeta inherit from type, not ABCMeta.
Apr 4, 2017
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17 changes: 8 additions & 9 deletions stdlib/3.4/enum.pyi
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Original file line number Diff line number Diff line change
@@ -1,12 +1,13 @@
# FIXME: Stub incomplete, ommissions include:
# * the metaclass
# * _sunder_ methods with their transformations

import sys
from typing import List, Any, TypeVar, Union
from typing import List, Any, TypeVar, Union, Iterable, Iterator, TypeVar, Generic, Type

_T = TypeVar('_T', bound=Enum)

class Enum:
def __new__(cls, value: Any) -> None: ...
class EnumMeta(type, Iterable[Enum]):
def __iter__(self: Type[_T]) -> Iterator[_T]: ... # type: ignore

class Enum(metaclass=EnumMeta):
def __new__(cls: Type[_T], value: Any) -> _T: ...
def __repr__(self) -> str: ...
def __str__(self) -> str: ...
def __dir__(self) -> List[str]: ...
Expand All @@ -20,8 +21,6 @@ class Enum:
class IntEnum(int, Enum):
value = ... # type: int

_T = TypeVar('_T')

def unique(enumeration: _T) -> _T: ...
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I thought this might break because of the new bound on _T, since this decorator applies to Enum classes, not Enum instances. But I tried it and it seems to work with mypy.

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Oh, hm, that might be by accident, or because something defaults to Any when mypy doesn't understand it. Would be nice to try this and see what the reveal_type(unique(Color)) actually says.

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$ cat ../bin/enumu.py 
import enum

@enum.unique
class X(enum.Enum):
    a = 1
    b = 2
reveal_type(X)

$ mypy --custom-typeshed-dir . ../bin/enumu.py 
../bin/enumu.py:7: error: Revealed type is 'def (value: Any) -> enumu.X'

This looks right to me.

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Hm...

import enum
class Colors(enum.Enum):
  RED = 1
  GREEN = 2
  BLUE= 3
X = unique(Colors)
reveal_type(X)

Gives

__tmp__.py:12: error: Type argument 1 of "unique" has incompatible value "Colors"
__tmp__.py:13: error: Revealed type is 'def (value: Any) -> __tmp__.Colors'

(Sorry the line numbers are offset, it's about the last two lines.)

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Interesting, so it works differently when used as a decorator. That seems like a mypy bug.

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Oh, that's not how it's supposed to be used. As a class decorator it does indeed work as expected. Not sure why or how.

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Maybe to be safe we should give unique its own TypeVar for now.


if sys.version_info >= (3, 6):
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