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Class Based Decorators and Representation ()

I tried to ensure that my class-based decorator supported the behavior of the repr()original wrapped function (according to how the decorator functools.wrapsworks on functions). I am using python 3.3.

First I tried functools:

import functools

class ClassBasedDecorator():
    def __init__(self, fn):
        self.fn = fn
        functools.update_wrapper(self, fn)
    def __call__(self, *args, **kwargs):
        self.fn(*args, **kwargs)

@ClassBasedDecorator
def wrapped(text):
    pass

But when I call repr()on the decorated function, I get:

>>> repr(wrapped)
'<__main__.ClassBasedDecorator object at 0x2d8860b6850>'

Ok, so I tried setting up __repr__my decorator method , which should be called repr().

Use functools again:

class ClassBasedDecorator():
    def __init__(self, fn):
        self.fn = fn
        functools.update_wrapper(
            self, fn,
            assigned=functools.WRAPPER_ASSIGNMENTS + ('__repr__',)
        )
    def __call__(self, *args, **kwargs):
        self.fn(*args, **kwargs)

It does not change the output, but something interesting happens:

>>> repr(wrapped)
'<__main__.ClassBasedDecorator object at 0x2d8860b69d0>'
>>> wrapped.__repr__()
'<function wrapped at 0x2d8860a9710>'

Explicitly setting the __repr__decorator instance method has the same effect.

repr(instance) instance.__class__.__repr__(instance). , overriden __repr__ .

, :

  • repr(instance) instance.__class__.__repr__(instance) instance.__repr__()? - ?
  • , functools.wraps , ( repr() )?
+3
1

( ), . a __repr__ , ; type(class).__repr__(class) , class.__repr__() , self .

__repr__:

class ClassBasedDecorator():
    def __init__(self, fn):
        self.fn = fn
        functools.update_wrapper(self, fn)
    def __call__(self, *args, **kwargs):
        self.fn(*args, **kwargs)
    def __repr__(self):
        return repr(self.fn)

. __module__, __name__ __doc__ __dict__, -.

+6

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