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annotate python/mutable_defaults.py @ 177:6ae566bb1a99

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add an example of lack of python closures
author Jeff Hammel <jhammel@mozilla.com>
date Thu, 03 Nov 2011 10:39:22 -0700
parents 70544c7406e2
children 434c65593612
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91
70544c7406e2 add illustration program for mutable arguments, since this comes up a bunch
Jeff Hammel <jhammel@mozilla.com>
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1 #!/usr/bin/env python
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2
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3 class Foo(object):
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4 def __init__(self, mutable=['default']):
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5 self.foo = mutable
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6 self.foo.append(1)
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7
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8 if __name__ == '__main__':
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9 bar = Foo()
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10 print len(bar.foo)
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11 fleem = Foo()
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12 print len(fleem.foo)
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13 assert len(fleem.foo) == 2, "Don't use default mutable arguments!"