too-many-ancestors / R0901ΒΆ
Message emitted:
Too many ancestors (%s/%s)
Description:
Used when class has too many parent classes, try to reduce this to get a simpler (and so easier to use) class.
Problematic code:
class Animal: ...
class BeakyAnimal(Animal): ...
class FurryAnimal(Animal): ...
class Swimmer(Animal): ...
class EggLayer(Animal): ...
class VenomousAnimal(Animal): ...
class ProtectedSpecie(Animal): ...
class BeaverTailedAnimal(Animal): ...
class Vertebrate(Animal): ...
# max of 7 by default, can be configured
# each edge of a diamond inheritance counts
class Playtypus( # [too-many-ancestors]
BeakyAnimal,
FurryAnimal,
Swimmer,
EggLayer,
VenomousAnimal,
ProtectedSpecie,
BeaverTailedAnimal,
Vertebrate,
):
pass
Correct code:
class Animal:
beaver_tailed: bool
can_swim: bool
has_beak: bool
has_fur: bool
has_vertebrae: bool
lays_egg: bool
protected_specie: bool
venomous: bool
class Invertebrate(Animal):
has_vertebrae = False
class Vertebrate(Animal):
has_vertebrae = True
class Mammal(Vertebrate):
has_beak = False
has_fur = True
lays_egg = False
venomous = False
class Playtypus(Mammal):
beaver_tailed = True
can_swim = True
has_beak = True
lays_egg = False
protected_specie = True
venomous = True
Created by the design checker.