Am 30.11.2012 12:11, schrieb andrea crotti:
I wrote a script, refactored it and then introducing a bug as below:
def record_things():
out.write("Hello world")
This is a function. Since "out" is not a local variable, it is looked up
in the surrounding namespace at the time the function is called.
if __name__ == '__main__':
with open('output', 'w') as out:
record_things()
This is not in a function, so binding variables affects the containing
namespace. This includes binding the context manager to "out". Note that
you could have moved the whole code into a function (e.g. one called
main()) and then you would have gotten the expected failure.
What my explanation might be is that the "out" is declared at module
level somehow, but that's not really intuitive and looks wrong, and
works both on Python 2.7 and 3.2..
Other than in C/C++/Java and others, indention doesn't introduce a new
scope, but I understand your intuition. Even simpler, this is how my
early Python code looked like, in the absence of the C ternary operator
and the distinction between a variable declaration and an assignment:
foo = None
if some_condition:
foo = 'bar'
else:
foo = 'baz'
More idiomatic would have been this:
if some_condition:
foo = 'bar'
else:
foo = 'baz'
Summary: I'd say that everything is fine. ;)
Uli
--
http://mail.python.org/mailman/listinfo/python-list
