Hi,
When inheriting from "dict" and overriding methods, W0613 is issued on some
methods:
===
class DictArgInstance(dict):
def __delitem__(self, key):
raise TypeError('attempt to modify read-only dictionary')
def __setitem__(self, key, value):
raise TypeError('attempt to modify read-only dictionary')
def clear(self):
raise TypeError('attempt to modify read-only dictionary')
def pop(self, key, default):
raise TypeError('attempt to modify read-only dictionary')
def popitem(self):
raise TypeError('attempt to modify read-only dictionary')
def setdefault(self, key, default):
raise TypeError('attempt to modify read-only dictionary')
def update(self, d, **kvargs):
raise TypeError('attempt to modify read-only dictionary')
===
W0613: 12:DictArgInstance.pop: Unused argument 'default'
W0613: 12:DictArgInstance.pop: Unused argument 'key'
W0613: 18:DictArgInstance.setdefault: Unused argument 'default'
W0613: 18:DictArgInstance.setdefault: Unused argument 'key'
W0613: 21:DictArgInstance.update: Unused argument 'kvargs'
W0613: 21:DictArgInstance.update: Unused argument 'd'
===
Apparently "__delitem__" and "__setitem__" are recognized as super class
methods and W0613 is suppressed there. But that is not the case for "pop",
"setdefault" and "update".
As "dict" is implemented in native code, the way to get information about it is
through introspection. I have been unable to find "__code__" attributes on the
problematic methods though. Does anyone know how to get information about
argument count and names for methods implemented as <type 'method_descriptor'>?
An alternative to introspection would be to have hardcoded information about
built-in classes, but that could get outdated when new optional arguments are
added in new Python versions. Also it would only solve the problem for classes
from Python itself.
The fact that a method overrides another, as opposed to defining a new method,
is easy to check. Therefore, an alternative would be to suppress W0613 when a
method is overridden, even if the arguments of the method in the super class
cannot be determined.
Bye,
Maarten
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