Fixed #29253 -- Made method_decorator(list) copy attributes.
This commit is contained in:
Chris Jerdonek
Tim Graham
parent
a480ef89ad
commit
fdc936c913
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@ -12,6 +12,44 @@ class classonlymethod(classmethod):
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return super().__get__(instance, cls)
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def _update_method_wrapper(_wrapper, decorator):
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# _multi_decorate()'s bound_method isn't available in this scope. Cheat by
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# using it on a dummy function.
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@decorator
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def dummy(*args, **kwargs):
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pass
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update_wrapper(_wrapper, dummy)
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def _multi_decorate(decorators, method):
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"""
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Decorate `method` with one or more function decorators. `decorators` can be
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a single decorator or an iterable of decorators.
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"""
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if hasattr(decorators, '__iter__'):
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# Apply a list/tuple of decorators if 'decorators' is one. Decorator
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# functions are applied so that the call order is the same as the
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# order in which they appear in the iterable.
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decorators = decorators[::-1]
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else:
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decorators = [decorators]
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def _wrapper(self, *args, **kwargs):
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# bound_method has the signature that 'decorator' expects i.e. no
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# 'self' argument.
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bound_method = method.__get__(self, type(self))
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for dec in decorators:
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bound_method = dec(bound_method)
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return bound_method(*args, **kwargs)
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# Copy any attributes that a decorator adds to the function it decorates.
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for dec in decorators:
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_update_method_wrapper(_wrapper, dec)
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# Preserve any existing attributes of 'method', including the name.
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update_wrapper(_wrapper, method)
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return _wrapper
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def method_decorator(decorator, name=''):
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"""
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Convert a function decorator into a method decorator
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@ -21,70 +59,30 @@ def method_decorator(decorator, name=''):
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# defined on. If 'obj' is a class, the 'name' is required to be the name
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# of the method that will be decorated.
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def _dec(obj):
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is_class = isinstance(obj, type)
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if is_class:
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if name and hasattr(obj, name):
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func = getattr(obj, name)
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if not callable(func):
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raise TypeError(
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"Cannot decorate '{0}' as it isn't a callable "
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"attribute of {1} ({2})".format(name, obj, func)
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)
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else:
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raise ValueError(
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"The keyword argument `name` must be the name of a method "
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"of the decorated class: {0}. Got '{1}' instead".format(
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obj, name,
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)
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)
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else:
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func = obj
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if not isinstance(obj, type):
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return _multi_decorate(decorator, obj)
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if not (name and hasattr(obj, name)):
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raise ValueError(
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"The keyword argument `name` must be the name of a method "
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"of the decorated class: %s. Got '%s' instead." % (obj, name)
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)
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method = getattr(obj, name)
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if not callable(method):
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raise TypeError(
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"Cannot decorate '%s' as it isn't a callable attribute of "
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"%s (%s)." % (name, obj, method)
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)
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_wrapper = _multi_decorate(decorator, method)
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setattr(obj, name, _wrapper)
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return obj
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def decorate(function):
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"""
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Apply a list/tuple of decorators if decorator is one. Decorator
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functions are applied so that the call order is the same as the
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order in which they appear in the iterable.
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"""
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if hasattr(decorator, '__iter__'):
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for dec in decorator[::-1]:
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function = dec(function)
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return function
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return decorator(function)
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def _wrapper(self, *args, **kwargs):
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@decorate
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def bound_func(*args2, **kwargs2):
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return func.__get__(self, type(self))(*args2, **kwargs2)
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# bound_func has the signature that 'decorator' expects i.e. no
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# 'self' argument, but it is a closure over self so it can call
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# 'func' correctly.
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return bound_func(*args, **kwargs)
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# In case 'decorator' adds attributes to the function it decorates, we
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# want to copy those. We don't have access to bound_func in this scope,
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# but we can cheat by using it on a dummy function.
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@decorate
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def dummy(*args, **kwargs):
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pass
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update_wrapper(_wrapper, dummy)
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# Need to preserve any existing attributes of 'func', including the name.
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update_wrapper(_wrapper, func)
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if is_class:
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setattr(obj, name, _wrapper)
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return obj
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return _wrapper
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# Don't worry about making _dec look similar to a list/tuple as it's rather
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# meaningless.
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if not hasattr(decorator, '__iter__'):
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update_wrapper(_dec, decorator)
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# Change the name to aid debugging.
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if hasattr(decorator, '__name__'):
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_dec.__name__ = 'method_decorator(%s)' % decorator.__name__
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else:
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_dec.__name__ = 'method_decorator(%s)' % decorator.__class__.__name__
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obj = decorator if hasattr(decorator, '__name__') else decorator.__class__
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_dec.__name__ = 'method_decorator(%s)' % obj.__name__
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return _dec
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@ -168,7 +168,7 @@ def myattr_dec(func):
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def wrapper(*args, **kwargs):
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return func(*args, **kwargs)
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wrapper.myattr = True
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return wraps(func)(wrapper)
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return wrapper
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myattr_dec_m = method_decorator(myattr_dec)
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@ -178,7 +178,7 @@ def myattr2_dec(func):
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def wrapper(*args, **kwargs):
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return func(*args, **kwargs)
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wrapper.myattr2 = True
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return wraps(func)(wrapper)
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return wrapper
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myattr2_dec_m = method_decorator(myattr2_dec)
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@ -209,13 +209,23 @@ class MethodDecoratorTests(SimpleTestCase):
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def test_preserve_attributes(self):
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# Sanity check myattr_dec and myattr2_dec
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@myattr_dec
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def func():
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pass
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self.assertIs(getattr(func, 'myattr', False), True)
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@myattr2_dec
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def func():
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pass
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self.assertIs(getattr(func, 'myattr2', False), True)
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@myattr_dec
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@myattr2_dec
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def func():
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pass
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self.assertIs(getattr(func, 'myattr', False), True)
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self.assertIs(getattr(func, 'myattr2', False), True)
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self.assertIs(getattr(func, 'myattr2', False), False)
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# Decorate using method_decorator() on the method.
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class TestPlain:
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@ -235,16 +245,23 @@ class MethodDecoratorTests(SimpleTestCase):
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"A method"
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pass
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# Decorate using an iterable of decorators.
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decorators = (myattr_dec_m, myattr2_dec_m)
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@method_decorator(decorators, "method")
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class TestIterable:
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# Decorate using an iterable of function decorators.
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@method_decorator((myattr_dec, myattr2_dec), 'method')
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class TestFunctionIterable:
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def method(self):
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"A method"
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pass
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tests = (TestPlain, TestMethodAndClass, TestIterable)
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# Decorate using an iterable of method decorators.
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decorators = (myattr_dec_m, myattr2_dec_m)
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@method_decorator(decorators, "method")
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class TestMethodIterable:
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def method(self):
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"A method"
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pass
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tests = (TestPlain, TestMethodAndClass, TestFunctionIterable, TestMethodIterable)
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for Test in tests:
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with self.subTest(Test=Test):
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self.assertIs(getattr(Test().method, 'myattr', False), True)
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