Fastest technique for string concatenation
Steven D'Aprano
steve at REMOVE-THIS-cybersource.com.au
Sat Oct 2 22:50:43 EDT 2010
On Sat, 02 Oct 2010 13:17:02 -0700, Carey Tilden wrote:
> Have you profiled an application and found string concatenation to be
> a performance bottleneck? I would be surprised, but it's always
> possible. If not, I'd suggest you choose the technique that is most
> clear and concise, and worry about performance only if it becomes a
> real issue.
While I agree with your general point about premature optimization, I
would not be the tiniest bit surprised to discover that string
concatenation was a performance bottleneck -- and that it only shows up
under some platforms and not others!
Repeated string concatenation risks being an O(n**2) algorithm, which
performs terribly. Last year there was a bug report of awful performance
in the httplib module that only effected Windows users:
http://www.mail-archive.com/python-dev%40python.org/msg40692.html
httplib was FOUR HUNDRED times slower than IE at copying a file over a
local network. Eventually the fault was tracked down to repeated string
concatenation in the module:
http://www.mail-archive.com/python-dev%40python.org/msg41150.html
It costs nothing to avoid repeated string concatenation even prior to
demonstrating a problem.
--
Steven
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