Snippet to get all local classes from a module

Question

I'm working on a project which due to the complexity of the business logic has had to pull out some classes to do computation related to some values in a database. To link the code and database, both when inserting and selecting, I need to get a list of all the class names contained within a single file. It works for me, but is this a sane approach?

import inspect
import my_module
my_module_class_names = [
 name for name, clazz in inspect.getmembers(my_module, inspect.isclass)
 if clazz.__module__ == my_module.__name__
]

• inspect.getmembers(my_module, inspect.isclass) gets any class members of my_module.
• if clazz.__module__ == my_module.__name__ ensures that classes imported into my_module are excluded from the list. This is the main reason I'm asking for a review - I only thought to include this clause because I had already imported other classes, and therefore the list had extraneous members.

Alternatively, from within my_module:

import inspect
import sys
def class_names() -> List[str]:
 return [
 name for name, clazz in inspect.getmembers(sys.modules[__name__], inspect.isclass)
 if clazz.__module__ == sys.modules[__name__].__name__
 ]

Answer 1

I have already used similar code and it looks rather fine. Some nitpicks:

• I’d name the variable cls to mimic the name often used as first parameters of @classmethods; or class_ as it is more common;
• I’d store a list of classes intead of a list of names, this feels more directly usable (and names are still stored as cls.__name__ if need be);
• sys.modules[__name__].__name__ should be just __name__.

---

Alternatively, since these classes seems related to each other, you may have an inheritance tree; or maybe a common base class. In this case, you could be even more specific using something such as:

[cls for _, cls in inspect.getmembers(my_module, inspect.isclass) if issubclass(cls, my_module.CommonBase)]

or

my_module.CommonBase.__subclasses__()

if there really is a single level of inheritance, but I wouldn't count much on it as it can break so easily.

• l0b0: Excellent! I do need the actual class names rather than the types, and I don't have a class hierarchy, but this can serve as basically a recipe for anyone who wants either variant of this pattern.