[issue30040] new empty dict can be more small
Josh Rosenberg
report at bugs.python.org
Mon Apr 17 21:44:38 EDT 2017
Josh Rosenberg added the comment:
For the record, legitimate case when many empty dicts are created, and few are populated, is the collections-free approach to defaultdict(dict):
mydict.setdefault(key1, {})[key2] = val
For, say, 100 unique key1s, and 10,000 total key1/key2 pairs, you'd create 10,000 empty dicts, discarding 9,900 of them. Granted, collections.defaultdict(dict) is even better (avoids the 9,900 unused dicts entirely), but I see the setdefault pattern enough, usually with list or dict, that it's not totally unreasonable to account for it.
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nosy: +josh.r
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<http://bugs.python.org/issue30040>
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