Finding intransitive subclass relationships in python

transitivity.py

"""
transitivity.py
Author: Naftali Harris

Run this in a clean virtualenv to only find intransitive triples in the stdlib.
"""

import pkgutil
import inspect
import collections
from importlib import import_module


def all_classes(module):
    return set([x[1] for x in inspect.getmembers(module, inspect.isclass)])


def all_python_classes():
    res = set()
    for module_loader, name, ispkg in pkgutil.walk_packages():
        try:
            module = import_module(name)
        except:
            print name
        else:
            res |= all_classes(module)

    res |= all_classes(__builtins__)
    return res


def short_name(A):
    return A.__module__ + "." + A.__name__


def get_bad_triplets(types):
    counts = collections.defaultdict(int)
    for t1 in types:
        for t2 in types:
            if not issubclass(t1, t2):
                continue
            for t3 in types:
                if issubclass(t2, t3):
                    counts["eligible"] += 1
                    if not issubclass(t1, t3):
                        counts["intransitive"] += 1
                        counts[("_", short_name(t2), short_name(t3))] += 1

    return counts


if __name__ == "__main__":
    types = all_python_classes()
    counts = get_bad_triplets(types)
    for triplet, count in sorted(counts.items(), key=lambda x: -x[1]):
        print ("%d\t%s" % (count, triplet)).replace("'", '')

    print len(types)