Is it possible to wrap this in a Python "with" statement?

Question

Is it possible to use it to achieve the following? (using the "with" keyword or not)

Before:

try:
    raise Exception("hello")
except Exception as e:
    print "GOT IT"

Desired effect:

def safety():
    try:
        yield
    except Exception as e:
        print "GOT IT"

with safety():
    raise Exception("hello")

It just makes the code so much cleaner. Currently running the second snippet gives the error:

Traceback (most recent call last):
  File "testing.py", line 25, in <module>
    with safety():
AttributeError: __exit__

what do you want to do? what is the expected behaviour? do you want to basically have giving a code example doesn't describe what you want to achieve. — Alexander Oh
– Alexander Oh, Commented Jan 13, 2016 at 20:45
I think he wants the resulting code behave like the first example. Can't think of a different interpretation TBH — Markus Unterwaditzer
– Markus Unterwaditzer, Commented Jan 13, 2016 at 20:47
@MarkusUnterwaditzer: It might be hard to understand because it doesn't make sense to do that. You shouldn't attempt to replicate a try/except block with with. — Vincent Savard
– Vincent Savard, Commented Jan 13, 2016 at 20:49
using the with statement is one option the other one is to decorate the function. if you want this at function scope it might be cleaner: python-3-patterns-idioms-test.readthedocs.org/en/latest/… on a side note: syntax error is also an exception that looks dangerous in python. — Alexander Oh
– Alexander Oh, Commented Jan 13, 2016 at 20:50

Markus Unterwaditzer · Accepted Answer · 2016-01-13 20:45:49Z

10

You were so close!

from contextlib import contextmanager

@contextmanager
def safety():
    try:
        yield
    except Exception as e:
        print "GOT IT"

with safety():
    raise Exception("hello")

answered Jan 13, 2016 at 20:45

Markus Unterwaditzer

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3 Comments

Alexander Oh Over a year ago

potentially precisely what the OP wants.

ed928 Over a year ago

Oh snap, that was fast. Thank you sir.

hpaulj Over a year ago

Effectively the contextmanager adds the missing .__exit__ attribute.

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