optimization question

[Andrew Koenig]

>> Doesn't string qualify?

Steve> Only before you subclass it to optimize slicing.

Sorry -- my question was too terse.  I'll elaborate:

My understanding is that because strings are immutable, any Python
implementation is permitted to disregard object identity when
it computes string values.  So, if I write

        a = "hello, world"
        b = a[0:5]

the implementation is permitted to cause a and b to refer to two
different subsequences of the same part of memory.  I understand that
present implementations do not behave this way in general, but I don't
think there's any basis for assuming that no implementation will ever
behave this way.  Am I right?

-- 
Andrew Koenig, ark at research.att.com, http://www.research.att.com/info/ark