Python function/block timer

timer.py

from __future__ import print_function
from functools import wraps
from time import time

__all__ = ['timer']

def timer(msg=None):

    def is_callable(thing):
        return getattr(thing, '__call__', None)

    class Timer(object):
        msg = ''
        func = None
        before = None

        def __init__(self, func=None, msg=''):
            self.func = func
            self.msg = msg

        def __call__(self, *args, **kwargs):
            if self.func:
                return self._runner(self.func, args, kwargs, msg=self.msg)
            elif not kwargs and len(args) == 1 and is_callable(args[0]):
                func = args[0]
                @wraps(func)
                def wrapped(*args, **kwargs):
                    return self._runner(func, args, kwargs, msg=self.msg)
                return wrapped

        def __enter__(self):
            self.before = time()
        def __exit__(self, *args):
            self.after = time()
            self._log(self.msg, self.after - self.before)

        @classmethod
        def _runner(cls, func, args, kwargs, msg=''):
            before = time()
            res = func(*args, **kwargs)
            after = time()
            cls._log(msg, after - before)
            return res

        @staticmethod
        def _log(msg, time):
            print('%s %f' % (msg, time))

    # with timer():
    if msg is None:
        return Timer()
    # @timer
    elif is_callable(msg):
        return wraps(msg)(Timer(func=msg))
    # @timer('notes')
    return Timer(msg=msg)


if __name__ == '__main__':
    @timer
    def foo():  pass
    foo()

    @timer('decorator with comments')
    def baz():  pass
    baz()

    with timer('with statement with comments'):
        with timer():
            pass