In some cases a comparison with operators ==, or != will always return True or always return False. When this happens,
the comparison and all its dependent code can simply be removed. This includes:
- comparing unrelated builtin types such as string and integer.
- comparing class instances which do not implement
__eq__ or __ne__ to an object of a different type (builtin or from
an unrelated class which also doesn’t implement __eq__ or __ne__).
Noncompliant code example
foo = 1 == "1" # Noncompliant. Always False.
foo = 1 != "1" # Noncompliant. Always True.
class A:
pass
myvar = A() == 1 # Noncompliant. Always False.
myvar = A() != 1 # Noncompliant. Always True.
Compliant solution
foo = 1 == int("1")
foo = str(1) != "1"
class Eq:
def __eq__(self, other):
return True
myvar = Eq() == 1
myvar = 1 == Eq()
myvar = Eq() != 1 # Ok. "__ne__" calls "__eq__" by default
myvar = 1 != Eq()
