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

python

prompt-engineering

functions

recursion

byAlex Kataev·Feb 17, 2025

# Because who doesn't want to find their own descendants?
Cls = globals()['MyClass'] # Change 'MyClass' to your class name
# Gather them children!
subclasses = Cls.__subclasses__()

Quickly unearth subclasses of 'MyClass':

Obtain class object using globals():
```
Cls = globals()['MyClass']
```
Outline direct children with __subclasses__():
```
subclasses = Cls.__subclasses__()
```

Dig deeper with recursion

To unmask all layers of subclasses, not just the direct children, you need to gather all generations:

def find_all_kids(cls):
    """Find all children, grandchildren, and so on for a class."""
    for kiddo in cls.__subclasses__():
        yield kiddo
        yield from find_all_kids(kiddo) # recursive magic

# Use example
all_kids = list(find_all_kids(Cls)) # It's a family reunion!

Import to find more kids

__subclasses__() only finds subclasses that have already been imported. To ensure you have a full house at the family reunion:

Import the guests you know are coming

Use importlib for the surprise guests:

import importlib
module = importlib.import_module('module_name') # Module your class might be chilling in
Cls = getattr(module, 'MyClass') # The name of your class

`__init_subclass__` for keeping tabs on the kids

__init_subclass__ lets you keep tabs on your descendants (in Python 3.6+). Every time a new subclass is created, it gets added to a list:

class Base:
    kids = []  # Where the kids go

    def __init_subclass__(cls, **kwargs):
        super().__init_subclass__(**kwargs)
        Base.kids.append(cls)  # Found a kid? Add it to the list!