david stanek's digressions

Python's super built-in has always bugged me. I'm talking about something much more superficial than James Knight's thoughts on it being harmful. I'm talking out its signature. I dislike the fact that it requires the current class and instance to be passed in. For example:

class SubClass(BaseClass):

    def method(self, arg, this=that):
        super(SubClass, self).method(arg, this)

To avoid doing an real work I hacked together an alternative implementation. I was able to get something that appears to work correctly, but I can't guarantee it. With my new super the code would look like:

from better_super import super

class SubClass(BaseClass):

    def method(self, arg, this=that):
        super().method(arg, this)

This should not be used in any real production code. There are likely bugs lurking in corner cases and strange failure modes. It's also four times slower than the built-in super.

It was still interesting to explore the implementation and I learned a bit about frames in the process.

My hacky implementation:

# better_super.py
import inspect as _inspect
from __builtin__ import super as _builtin_super


def _what_class_am_i_in(mro, func_name, func_code):
    for c in mro:
        if getattr(c, func_name).func_code is func_code:
            return c
    return None


def super():
    frame = _inspect.currentframe().f_back
    arg_info = _inspect.getargvalues(frame)
    self = arg_info[3][arg_info[0][0]]
    mro = _inspect.getmro(self.\__class__)
    method_name = frame.f_code.co_name
    code_obj = frame.f_code
    cls = _what_class_am_i_in(mro, method_name, code_obj)
    return _builtin_super(cls, self)

I'd love to hear about other ways to implement this. Have you tried yet?