On Wed, Dec 04, 2019 at 07:11:39PM +1300, Greg Ewing wrote:
> On 4/12/19 12:53 pm, Soni L. wrote:
> >Okay, sometimes it's also used for that. But the main use-case is for
> >lowering RAM usage for immutable objects.
>
> Citation needed. If that's true, why does Python intern
> names used in code, but not strings in general?
py> s = "ab1234z"
py> t = "ab1234z"
py> s is t
True
CPython doesn't *just* intern names. Nor does it intern every string.
But it interns a lot of strings which aren't used as names, including
some which cannot be used as names:
py> a = "+"
py> b = "+"
py> a is b
True
It also interns many ints, and they can't be used as names at all.
Here's a good explanation of interning in Python 2.7, including a great
example of how interning strings can reduce memory usage by 68%.
http://guilload.com/python-string-interning/
--
Steven
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