How do I check (at runtime) if one class is a subclass of another?

python subclass assert
snakile picture snakile · Feb 6, 2011 · Viewed 107k times · Source

Let's say that I have a class Suit and four subclasses of suit: Heart, Spade, Diamond, Club.

class Suit:
   ...
class Heart(Suit):
   ...
class Spade(Suit):
   ...
class Diamond(Suit):
   ...
class Club(Suit):
   ...

I have a method which receives a suit as a parameter, which is a class object, not an instance. More precisely, it may receive only one of the four values: Heart, Spade, Diamond, Club. How can I make an assertion which ensures such a thing? Something like:

def my_method(suit):
   assert(suit subclass of Suit)
   ...

I'm using Python 3.

Answer

user97370 picture user97370 · Feb 6, 2011

You can use issubclass() like this assert issubclass(suit, Suit).

Related questions

How to find all the subclasses of a class given its name?

I need a working approach of getting all classes that are inherited from a base class in Python.

Read More
Why aren't superclass __init__ methods automatically invoked?

Why did the Python designers decide that subclasses' __init__() methods don't automatically call the __init__() methods of their superclasses, as in some other languages? Is the Pythonic and recommended idiom really like the following? class Superclass(object): def __init__(self): …

Read More
How do you use the ellipsis slicing syntax in Python?

This came up in Hidden features of Python, but I can't see good documentation or examples that explain how the feature works.

Read More