On Sun, 10 Nov 2013 09:14:28 +1100, Chris Angelico wrote:
> And
> as is typical of python-list, it's this extremely minor point that
> became the new course of the thread -
You say that as if it were a bad thing :-P
> my main point was not whether all,
> some, or no strings get interned, but that string interning makes the
> storage space of duplicate strings immaterial :)
True. It's not just a memory saver[1], but a time saver too. Using Python
3.3:
py> from timeit import Timer
py> t1 = Timer('s == t', setup='s = "a b"*10000; t = "a b"*10000')
py> t2 = Timer('s == t',
... setup='from sys import intern; s = intern("a b"*10000); '
... 't = intern("a b"*10000)')
py> min(t1.repeat(number=100000))
7.651959054172039
py> min(t2.repeat(number=100000))
0.00881262868642807
String equality does a short-cut of checking for identity; if the strings
are interned, they will be identical.
[1] Assuming that you actually do have duplicate strings. If every string
is unique, interning them potentially wastes memory.
--
Steven
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