Signature differs in overridden method PYL-W0222
Bug risk
Major
4 years ago
—
4 years old
Signature differs from overridden 'connectionLost' method
282 log.query("%s connected" % self.peerAddr)
283 self.unpickler = get_unpickler(insecure=settings.USE_INSECURE_UNPICKLER)
284
285 def connectionLost(self, reason):286 if reason.check(ConnectionDone):
287 log.query("%s disconnected" % self.peerAddr)
288 else:
Description
There are one (or more) legal parameters for an overridden method that are not legal for an overriding method. This will cause an error when the overriding method is called with a number of parameters that are legal for the overridden method. This violates the Liskov substitution principle. Read more about LSP [here] (https://en.wikipedia.org/wiki/Liskovsubstitutionprinciple).
Bad practice
class A:
def foobar(x, y=0):
return x + y
class B(A):
def foobar(x, y):
return x + 2*y
a = A()
a.foobar(1) # Valid
b = B()
b.foobar(1) # Invalid
Recommended
class A:
def foobar(x, y=0):
return x + y
class B(A):
def foobar(x, y=1):
return x + 2*y
a = A()
a.foobar(1) # Valid
b = B()
b.foobar(1) # Valid