[Python-Dev] Issue 2986: difflib.SequenceMatcher is partly broken (original) (raw)

Eli Bendersky eliben at gmail.com
Wed Jul 7 19:44:31 CEST 2010

Rather than reverting to Tim's undocumented vision, perhaps we should better articulate it by separating the general purpose matcher from an optimised text matcher.

For what it's worth, my benchmarking showed that modifying the heuristic to only kick in when there are more than 100 kinds of elements (Terry's option A) didn't affect the runtime of matching whatsoever, even when the heuristic does kick in. All it adds, really, is the overhead of a single 'if' statement. So it wouldn't be right to assume that somehow modifying the heuristic or allowing to turn it off will negatively affect performance in the special case Tim originally optimized for.

Eli

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