[英]type hinting in python
i have some problem to put type hinting in my python program. 我在将类型提示放入python程序时遇到一些问题。 it is from python 3.5. 它来自python 3.5。
With this example: 在此示例中:
# -*- coding: utf-8 -*-
import collections
import typing
XV = typing.TypeVar('XV')
class Coll(collections.OrderedDict[str, XV]):
def sorted(self) -> collections.OrderedDict[str, XV]:
dict_sorted = collections.OrderedDict() # type: collections.OrderedDict[str,XV]
for key in sorted(self.keys()):
dict_sorted[key] = self[key]
return dict_sorted
def __str__(self) -> str:
retour = "" # type:str
if len(self) == 0:
return ""
test = self.sorted() # type: collections.OrderedDict[str,XV]
for l in test:
if retour:
retour += "\n{0!s}".format(self[l])
else:
retour = "{0!s}".format(self[l])
return retour
def __repr__(self) -> str:
return self.__str__()
when i run mypy, i have the following: 当我运行mypy时,我有以下内容:
example.py:8: error: Invalid type "example.XV"
example.py: note: In function "__str__":
example.py:20: error: Invalid type "example.XV"
the thing i don't understand is why i have those errors. 我不明白的是为什么我有那些错误。
OrderedDict
is not a subclass of typing.Generic
and therefore cannot be parametrized. OrderedDict
不是类型的子类。 typing.Generic
,因此无法参数化。 However you may easily define the corresponding type as follows: 但是,您可以轻松定义相应的类型,如下所示:
from typing import MutableMapping, TypeVar
from collections import OrderedDict
KT = TypeVar('KT') # Key type.
VT = TypeVar('VT') # Value type.
class OrderedDictType(OrderedDict, MutableMapping[KT, VT], extra=OrderedDict):
__slots__ = ()
def __new__(cls, *args, **kwds):
raise TypeError("Type OrderedDictType cannot be instantiated;" +
" use OrderedDict() instead")
# isinstance check
a = OrderedDict()
assert isinstance(a, OrderedDictType)
You may then use it in all type hints : OrderedDictType[str,XV]
instead of OrderedDict[str,XV]
. 然后,您可以在所有类型提示中使用它: OrderedDictType[str,XV]
而不是OrderedDict[str,XV]
。
See https://docs.python.org/3/library/typing.html#user-defined-generic-types and typing.py
source for details and examples (I used the typing.List
class as an example). 有关详细信息和示例,请参见https://docs.python.org/3/library/typing.html#user-defined-generic-types和typing.py
源(我以typing.List
类为例)。
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