This chage more closely matches the behavior of `get` at runtime. Users can pass whatever they want in to the default
parameter and it will be returned if the key is absent. Additionally, `get` should return an `Optional` if called with
only one parameter.
```python
z = {'a': 22}
reveal_type(z.get('b'))
reveal_type(z.get('b', 22))
reveal_type(z.get('b', 'hello'))
```
Before:
```shell
test_get_default.py:2: error: Revealed type is 'builtins.int*'
test_get_default.py:3: error: Revealed type is 'builtins.int*'
test_get_default.py:4: error: Revealed type is 'builtins.int*'
test_get_default.py:4: error: Argument 2 to "get" of "dict" has incompatible type "str"; expected "int"
```
After:
```shell
test_get_default.py:2: error: Revealed type is 'Union[builtins.int*, builtins.None]'
test_get_default.py:3: error: Revealed type is 'builtins.int'
test_get_default.py:4: error: Revealed type is 'Union[builtins.int, builtins.str*]'
```
* Define __slots__ for object as Iterable[str] / Iterable[Union[str, unicode]]
* A string as __slots__ value is also valid and represents a single item
```
$ python3.4
Python 3.4.3 (default, Nov 17 2016, 01:08:31)
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> list(filter(None, [False, True]))
[True]
>>>
```
python/mypy#2380 showed a discrepancy between object and FunctionType in stdlib2. The first defined __doc__ to be str, the second Optional[str]. As FunctionType depends on object, this is no longer valid.
As suggested by @gvanrossum in python/mypy#2380, all __doc__ should be considered Optional.
(Final verdict was just to remove most __doc__ attributes since it's inherited from object.)
Reason: https://github.com/python/mypy/issues/328
* Revert "Make fromkeys() take an Iterable instead of a sequence. (#605)"
This reverts commit 66e8d4a14f.
* Revert "Make dict.fromkeys() a classmethod (which it is). (#604)"
This reverts commit 26dfcb6859.
* Add an explanation for fromkeys() being a staticmethod.
As of Python 2.7, you can pass in multiple iterables into some set
methods like union, intersection, difference, and update. So, for
example, `new_set = a.union(b, c)`.
This reverts commit d43adbe97e.
Here's a simple example of code that breaks with this PR:
from typing import Mapping, Dict, Tuple
a = {('0', '0'): 42} # type: Mapping[Tuple[str, str], int]
b = a.get(('1', '1'), 0)
This gives an error on the last line:
error: No overload variant of "get" of "dict" matches argument types [Tuple[builtins.str, builtins.str], builtins.int]
This was missing for some reason while the Python 2.7 stubs have it.
Sample test code:
% cat testtype.py
A = type('A', (), {})
print(A.__name__)
Results before:
% python -m mypy --py2 testtype.py
% python -m mypy testtype.py
testtype.py:1: error: Too many arguments for "type"
%
Results after: type checking passes in both modes.
