Get list of names of child classes in python

Question

If I had multiple classes inside another class, how would I get a list of the names of the child classes?

class commands:
    class hello:
        desc = "says hello"
    class exec:
        desc = "executes code"

My wish is to get a list of the commands similar to ["hello", "exec"]. So far I've only found information about subclasses and recursive classes but nothing about actually finding the names of these.

Context is similar to a help page. Example: `print(commands.hello.desc)` . I'm trying to work with getting a list of functions and extra information about them, but these are currently separated into classes and functions. — Floris_Fireball, Apr 09 '21 at 23:10
`commands.__dict__`, `vars(commands)`, or `dir(commands)` would output all members of the class, but that also includes methods and other variables. — ArjunSahlot, Apr 09 '21 at 23:12
Those aren't child classes. You'd have to introspect the class namespace, but there is no guarantee that the class objects were *defined* within the class body. Note, nested classes like this aren't a common pattern in Python, they serve little purpose. — juanpa.arrivillaga, Apr 09 '21 at 23:13
What would you suggest I should do for something like this? I tried using dictionaries for the same method, but then you use dict["item"] instead of dict.item, and the latter looks neater. — Floris_Fireball, Apr 09 '21 at 23:16
@Floris_Fireball, If dicts were like that in python, it wouldn't work because, if you were to have a item named "clear", then running it would cause collision due to dicts already having a clear method `dict.clear` — ArjunSahlot, Apr 09 '21 at 23:21
Oh, ok, I don't think the OP does either. This is definitely an XY problem. Fighting the syntax of Python to get it to something like, say, JavaScript, is just a losing battle. You'll get your "neater" syntax and the rest of the structure goes down the toilet — roganjosh, Apr 09 '21 at 23:32
What *problem do you expect to solve* by putting `hello` and `desc` inside a `commands` class, rather than at the top level of the file? What, conceptually, is "a commands"? Does it make sense for me to write code somewhere else like `x = commands()`? If not, it *should not be a class*. Classes aren't just there to make namespaces. The *module* already provides a namespace for you, anyway. — Karl Knechtel, Apr 10 '21 at 02:21

score 1 · Accepted Answer · answered Apr 10 '21 at 02:16

Any of these should work generally:

print([k for k, v in commands.__dict__.items() if isinstance(v, type)])

import inspect

print([k for k, v in commands.__dict__.items() if inspect.isclass(v)])

print([k for k, v in vars(commands).items() if isinstance(v, type)])

import inspect

print([k for k, v in vars(commands).items() if inspect.isclass(v)])

There are also more options in these SO threads:

All 4 commands output:

['hello', 'exec']

Tested on the following structure to ensure that nothing other than class instances would appear in the output:

class Other:
    pass


class commands:
    a = 2
    o = Other()

    class hello:
        desc = "says hello"

        def rand(self):
            pass

    class exec:
        desc = "executes code"

        def rand(self):
            pass

    def clear(self):
        pass

Get list of names of child classes in python

1 Answers1