Support launch_ipdb_on_exception as a function decorator

[alanbernstein]

For some time I have used this in my personal debug tools:

import ipdb

class Decontext(object):
    """
    Makes a context manager also act as decorator
    """
    def __init__(self, context_manager):
        self._cm = context_manager

    def __enter__(self):
        return self._cm.__enter__()

    def __exit__(self, *args, **kwds):
        return self._cm.__exit__(*args, **kwds)

    def __call__(self, func):
        def wrapper(*args, **kwds):
            with self:
                return func(*args, **kwds)
        return wrapper

pm = Decontext(ipdb.launch_ipdb_on_exception())

It allows me to do this:

from mydebugtools import pm

@pm
def main():
    # whatever

And ipdb is triggered on an exception at any level below that function in the call stack.

This is kind of a silly convenience thing, maybe just personal preference, but I thought others might benefit from seeing it. Would it be reasonable to add this functionality to ipdb? If so, would it be sensible to use this (not named pm), or is there a better way?

[gotcha]

It would be reasonable 😄

I'll let you come up with a good name and a PR.