[英](Python type hints) How to specify type being currently defined as the returned type from a method?
我想指定(作为类型提示)当前定义的类型作为方法的返回类型。
这是一个例子:
class Action(Enum):
ignore = 0
replace = 1
delete = 2
@classmethod
# I would like something like
# def idToObj(cls, elmId: int)->Action:
# but I cannot specify Action as the return type
# since it would generate the error
# NameError: name 'Action' is not defined
def idToObj(cls, elmId: int):
if not hasattr(cls, '_idToObjDict'):
cls._idToObjDict = {}
for elm in list(cls):
cls._idToObjDict[elm.value] = elm
return cls._idToObjDict[elmId]
理想情况下,我希望指定类似
def idToObj(cls, elmId: int)->Action:
谢谢。
在官方类型提示PEP中提到了这种情况:
当类型提示包含尚未定义的名称时,该定义可以表示为字符串文字,稍后再解析。
class Tree:
def __init__(self, left: Tree, right: Tree):
self.left = left
self.right = right
为了解决这个问题,我们写:
class Tree:
def __init__(self, left: 'Tree', right: 'Tree'):
self.left = left
self.right = right
以您的情况为:
def idToObj(cls, elmId: int)->'Action':
pass # classmethod body
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