我希望能够询问班级的__init__方法的参数是什么。简单的方法如下：
cls.__init__.__func__.__code__.co_varnames[:code.co_argcount]
但是，如果类有任何装饰器，那么这将不起作用。它将给出装饰器返回的函数的参数列表。我想回到原来的样子__init__方法并获取那些原始参数。对于装饰器，装饰器函数将在装饰器返回的函数的闭包中找到：
cls.__init__.__func__.__closure__[0]
然而，如果闭包中还有其他装饰器可能不时做的事情，那就更复杂了：
def Something(test):
def decorator(func):
def newfunc(self):
stuff = test
return func(self)
return newfunc
return decorator
def test():
class Test(object):
@Something(4)
def something(self):
print Test
return Test
test().something.__func__.__closure__
(<cell at 0xb7ce7584: int object at 0x81b208c>, <cell at 0xb7ce7614: function object at 0xb7ce6994>)
然后我必须决定是否想要来自装饰器的参数或来自原始函数的参数。装饰器返回的函数可以有*args and **kwargs为其参数。如果有多个装饰器并且我必须决定哪一个是我关心的怎么办？
那么，即使函数可能被修饰，查找函数参数的最佳方法是什么？另外，沿着装饰器链回到装饰函数的最佳方法是什么？
Update:
这实际上是我现在正在做的事情（为了保护被告的身份，姓名已更改）：
import abc
import collections
IGNORED_PARAMS = ("self",)
DEFAULT_PARAM_MAPPING = {}
DEFAULT_DEFAULT_PARAMS = {}
class DICT_MAPPING_Placeholder(object):
def __get__(self, obj, type):
DICT_MAPPING = {}
for key in type.PARAMS:
DICT_MAPPING[key] = None
for cls in type.mro():
if "__init__" in cls.__dict__:
cls.DICT_MAPPING = DICT_MAPPING
break
return DICT_MAPPING
class PARAM_MAPPING_Placeholder(object):
def __get__(self, obj, type):
for cls in type.mro():
if "__init__" in cls.__dict__:
cls.PARAM_MAPPING = DEFAULT_PARAM_MAPPING
break
return DEFAULT_PARAM_MAPPING
class DEFAULT_PARAMS_Placeholder(object):
def __get__(self, obj, type):
for cls in type.mro():
if "__init__" in cls.__dict__:
cls.DEFAULT_PARAMS = DEFAULT_DEFAULT_PARAMS
break
return DEFAULT_DEFAULT_PARAMS
class PARAMS_Placeholder(object):
def __get__(self, obj, type):
func = type.__init__.__func__
# unwrap decorators here
code = func.__code__
keys = list(code.co_varnames[:code.co_argcount])
for name in IGNORED_PARAMS:
try: keys.remove(name)
except ValueError: pass
for cls in type.mro():
if "__init__" in cls.__dict__:
cls.PARAMS = tuple(keys)
break
return tuple(keys)
class BaseMeta(abc.ABCMeta):
def __init__(self, name, bases, dict):
super(BaseMeta, self).__init__(name, bases, dict)
if "__init__" not in dict:
return
if "PARAMS" not in dict:
self.PARAMS = PARAMS_Placeholder()
if "DEFAULT_PARAMS" not in dict:
self.DEFAULT_PARAMS = DEFAULT_PARAMS_Placeholder()
if "PARAM_MAPPING" not in dict:
self.PARAM_MAPPING = PARAM_MAPPING_Placeholder()
if "DICT_MAPPING" not in dict:
self.DICT_MAPPING = DICT_MAPPING_Placeholder()
class Base(collections.Mapping):
__metaclass__ = BaseMeta
"""
Dict-like class that uses its __init__ params for default keys.
Override PARAMS, DEFAULT_PARAMS, PARAM_MAPPING, and DICT_MAPPING
in the subclass definition to give non-default behavior.
"""
def __init__(self):
pass
def __nonzero__(self):
"""Handle bool casting instead of __len__."""
return True
def __getitem__(self, key):
action = self.DICT_MAPPING[key]
if action is None:
return getattr(self, key)
try:
return action(self)
except AttributeError:
return getattr(self, action)
def __iter__(self):
return iter(self.DICT_MAPPING)
def __len__(self):
return len(self.DICT_MAPPING)
print Base.PARAMS
# ()
print dict(Base())
# {}
此时，Base 报告了四个内容的无趣值，并且实例的 dict 版本为空。但是，如果您创建子类，则可以覆盖四个中的任何一个，或者可以将其他参数包含到__init__:
class Sub1(Base):
def __init__(self, one, two):
super(Sub1, self).__init__()
self.one = one
self.two = two
Sub1.PARAMS
# ("one", "two")
dict(Sub1(1,2))
# {"one": 1, "two": 2}
class Sub2(Base):
PARAMS = ("first", "second")
def __init__(self, one, two):
super(Sub2, self).__init__()
self.first = one
self.second = two
Sub2.PARAMS
# ("first", "second")
dict(Sub2(1,2))
# {"first": 1, "second": 2}
