Python 装饰器处理文档字符串
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Python decorator handling docstrings
提问by Günther Jena
I have a problem using docstrings with decorators. Given the following example:
我在使用带有装饰器的文档字符串时遇到问题。给出以下示例：
def decorator(f):
def _decorator():
print 'decorator active'
f()
return _decorator
@decorator
def foo():
'''the magic foo function'''
print 'this is function foo'
help(foo)
Now the help doesn't show me the docstring of fooas expected, it shows:
现在帮助没有foo按预期向我显示文档字符串，它显示：
Help on function _decorator in module __main__:
_decorator()
Without the decorator, the help is correct:
没有装饰器，帮助是正确的：
Help on function foo in module __main__:
foo()
the magic foo function
I know, that the function foois wrapped by the decorator, and so the function object is not the function fooany more. But what is a nice solution to get the docstring (and the help) as expected?
我知道，该函数foo是由装饰器包装的，因此函数对象不再是函数foo。但是，按预期获取文档字符串（和帮助）的好方法是什么？
回答by P?r Wieslander
Use functools.wraps()to update the attributes of the decorator:
使用functools.wraps()更新装饰的属性：
from functools import wraps
def decorator(f):
@wraps(f)
def _decorator():
print 'decorator active'
f()
return _decorator
@decorator
def foo():
'''the magic foo function'''
print 'this is function foo'
help(foo)
Also see the Standard Library documentationfor functools.
另请参阅标准库文件的functools。
回答by Günther Jena
I found a solution, but don't know if it's really nice:
我找到了一个解决方案，但不知道它是否真的很好：
def decorator(f):
def _decorator():
print 'decorator active'
f()
_decorator.__name__=f.__name__
_decorator.__doc__=f.__doc__
return _decorator
The part with _decorator.__name__=f.__name__seems a little bit hideous... What do you think?
_decorator.__name__=f.__name__有的部分看起来有点可怕……你怎么看？
回答by Mark Byers
Take a look at functools.wraps: http://docs.python.org/library/functools.html
看看functools.wraps：http: //docs.python.org/library/functools.html
