我想从类继承只是为了向它的方法添加装饰器。
如果没有重新定义每个基类方法,是否有快捷方式?
答案 0 :(得分:0)
当然,你可以动态地做到这一点。假设你有一些课程:
>>> class Foo:
... def bar(self): print('bar')
... def baz(self): print('baz')
...
还有一位装饰师:
>>> def deco(f):
... def wrapper(self):
... print('decorated')
... return f(self)
... return wrapper
...
然后继承:
>>> class Foo2(Foo):
... pass
...
然后遍历原始类,并将装饰器应用于新的子类:
>>> for name, attr in vars(Foo).items():
... if callable(attr):
... setattr(Foo2, name, deco(attr))
...
因此...
>>> x = Foo2()
>>> x.bar()
decorated
bar
>>> x.baz()
decorated
baz
现在,使用if callable(attr)
可能不够严格。你可能想忽略“dunder”方法,所以改为:
for name, attr in vars(Foo):
if callable(attr) and not name.startswith('__'):
setattr(Foo2, name, attr)
可能更合适。取决于你的用例。
只是为了好玩,这里我们也可以使用type
构造函数:
In [17]: class Foo:
...: def bar(self): print('bar')
...: def baz(self): print('baz')
...:
In [18]: def deco(f):
...: def wrapper(self):
...: print('decorated')
...: return f(self)
...: return wrapper
...:
In [19]: Foo3 = type(
...: 'Foo3',
...: (Foo,),
...: {name:deco(attr) for name, attr in vars(Foo).items() if callable(attr)}
...: )
In [20]: y = Foo3()
In [21]: y.bar()
decorated
bar
In [22]: y.baz()
decorated
baz
答案 1 :(得分:0)
您可以使用类装饰器来封装整个作品
示例代码:
def deco(func):
"""Function decorator"""
def inner(*args, **kwargs):
print("decorated version")
return func(*args, **kwargs)
return inner
def decoclass(decorator):
"""Class decorator: decorates public methods with decorator"""
def outer(cls):
class inner(cls):
pass
for name in dir(cls):
if not name.startswith("_"): # ignore hidden and private members
# print("decorating", name) # uncomment for tests
attr = getattr(inner, name)
setattr(inner, name, decorator(attr))
return inner
return outer
class Foo:
"""Sample class""
def foo(self):
return "foo in Foo"
然后你可以使用它:
>>> @decoclass(deco)
class Foo2(Foo):
pass
>>> f = Foo2()
>>> f.foo()
decorated version
'foo in Foo'