Python speed and `pcre'

[Fredrik Lundh]

François Pinard <pinard at iro.umontreal.ca> wrote:
> I do not fully understand the cost of splitting.  If strings are immutable,
> there is really no need to copy a slice contents.

except that 1) each string needs an extra reference pointer
(as long as we're using refcounting, at least), and 2) that people
can easily end up in situations where huge strings are clogging
up all available memory, just because some part of their program
is hanging on on to a 2-character substring...

(fwiw, the unicode string type implements substring
support, using it for the "split" and "slice" methods.
still not sure if that's really a great idea...)

> Somewhere, it is said that some extra-space is allocated at end of sequences,
> to allow for some peaceful growth.  Does `str=str+str1' at least attempt
> to use of this extra-space?  It should, in my opinion.

how?  before you tell me, consider that strings are immutable,
and variable names are references.

</F>