At 02:38 PM 6/27/04 +0100, Armin Rigo wrote:
On Sat, Jun 19, 2004 at 03:40:07PM -0400, Raymond Hettinger wrote:
s = "" for e in iterable: s = s + e
Hum, it may not be impossible after all.
http://www.python.org/sf/980695 -> an idea that seems to work and only involves 3 pages of obfuscated code in new well-isolated functions of ceval.c. stringobject.c is unmodified.
Looks interesting. It appears the cost is added to cases that are likely to have longer execution times anyway. (i.e. the slow_add and slow_iadd cases.)
I notice that string_concatenate() doesn't cover the STORE_DEREF case, however. Was that intentional?
Last question: is this actually faster when 'e' is replaced by an expression that causes memory allocation? That is, isn't this *still* going to be an O(n**2) operation if the string has to be relocated on each addition?