[issue6637] non-empty defaultdict .copy() fails returning empty dict
Tom Clarke
report at bugs.python.org
Tue Aug 4 11:50:50 CEST 2009
Tom Clarke <t.clarke at ic.ac.uk> added the comment:
NB - (discussion of significance of this bug)
Defaultdict called with no argument is anomalous & this problem can be
avoided in such cases by using dict. However this is not possible if
default value can change and the documentation specifically defines
behavior when called with no parameter, so this case is allowed.
Furthermore this bug is unpleasant because when the default values are
never used it is very counterintuitive to imagine that the an error in
the default value function could have any effect on the output.
Possible solutions:
(1) raise error in this case, change documentation (I prefer)
(2) mend behaviour in this case
Best wishes, Tom
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<http://bugs.python.org/issue6637>
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