On 29/07/2010 07:32, Daniel Waterworth wrote:
Hi,
I'm not sure if this is a bug or not, I certainly didn't expect it. If
you create a file called test.py with the following contents,
The issue is that when your code is executed as a script it is run as
the __main__ module and not as the test module. When you import test you
then import the same module with a different name - and your Test class
is recreated (so __main__.Test is then different from test.Test). When
you import your code as test and it then reimports itself it is only
created once.
This *is* expected behaviour (not a bug), but it frequently confuses
even relatively experienced programmers (it can happen by accident and
cause hard to track down bugs) and I personally think that Python would
be improved by issuing a warning if a __main__ script reimports itself.
All the best,
Michael Foord
class Test:
pass
def test_1():
import test
print Test == test.Test
if __name__ == '__main__':
test_1()
and then run it ($ python test.py), it'll print False. Now try:
$python
import test
test.test_1()
and it'll print True. Is this behaviour expected? What was the
rationale for it if is?
Thanks,
Daniel
--
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