Mercurial > hg > config
diff python/mutable_defaults.py @ 91:70544c7406e2
add illustration program for mutable arguments, since this comes up a bunch
| author | Jeff Hammel <jhammel@mozilla.com> |
|---|---|
| date | Tue, 21 Sep 2010 08:30:19 -0700 |
| parents | |
| children | 434c65593612 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/python/mutable_defaults.py Tue Sep 21 08:30:19 2010 -0700 @@ -0,0 +1,13 @@ +#!/usr/bin/env python + +class Foo(object): + def __init__(self, mutable=['default']): + self.foo = mutable + self.foo.append(1) + +if __name__ == '__main__': + bar = Foo() + print len(bar.foo) + fleem = Foo() + print len(fleem.foo) + assert len(fleem.foo) == 2, "Don't use default mutable arguments!"