[Python-Dev] dict.addlist()
Phillip J. Eby
pje at telecommunity.com
Tue Jan 20 09:56:57 EST 2004
At 09:26 AM 1/20/04 -0500, Bob Ippolito wrote:
>There are other reasons to use setdefault. This one is pretty common
>though, but I think a more generic solution could be implemented.
>
>Perhaps:
>
>d.setdefault(k, factory=list).append(v) ?
+100. :) An excellent replacement for my recurring use of:
try:
return self._somemapping[key]
except:
self._somemapping[key] = value = somethingExpensive(key)
return value
That becomes simply:
return self._somemapping.setdefault(
key, factory=lambda: somethingExpensive(key)
)
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