[Python-Dev] Question about dictobject.c:lookdict_string
eyal.lotem at gmail.com
Mon Jun 11 06:55:50 CEST 2007
My question is specifically regarding the transition back from
lookdict_string (the initial value) to the general lookdict.
Currently, when a string-only dict is trying to look up any
non-string, it reverts back to a general lookdict.
Wouldn't it be better (especially in the more important case of a
string-key-only dict), to revert to the generic lookdict when a
non-string is inserted to the dict, rather than when one is being
This seems to me as it would shift this (admittedly very slight)
performance cost of a type ptr comparison from the read-access, to
write-access on all dicts (which means insertions of new keys in
non-string-only dicts may pay for another check, or that the lookdict
funcptr will be replaced by two funcptrs so that a different insertion
func on string-only dicts is used too [was tempted to say vtable
here, but that would add another dereference to lookups]).
It would also have the slight benefit of speeding up non-string
lookups in string-only dicts.
This does not seem like a significant issue, but as I know a lot of
effort went into optimizing dicts, I was wondering if I am missing
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