[pypy-issue] [issue781] Confusing error message on "with"

Ismael tracker at bugs.pypy.org
Wed Jul 6 05:46:33 CEST 2011

New submission from Ismael <ismaelgfk at gmail.com>:

Using the "with" statement wrongly results in a confusing error message.

Code (originally written by Alex Gaynor):

class Timer(object):
    def __enter__(self):
        self.start = time.time()
    def __exit__(self, exc_type, exc_val, tb):
        print "Section time: ", time.time() - self.start

#Note the error here, I call the class, not an instance
with Timer:


Compare the CPython 2.6 error:

ismael at chaos:~/Escritorio$ python slow.py 
Traceback (most recent call last):
  File "slow.py", line 31, in <module>
    with Timer:
TypeError: unbound method __enter__() must be called with Timer instance as
first argument (got nothing instead)

Against PyPy 1.5:

ismael at chaos:~/Escritorio$ ~/pypy/bin/pypy slow.py 
Traceback (most recent call last):
  File "app_main.py", line 53, in run_toplevel
  File "slow.py", line 31, in <module>
    with Timer:
AttributeError: __exit__

messages: 2738
nosy: Ismael, pypy-issue
priority: wish
release: 1.5
status: unread
title: Confusing error message on "with"

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