[Python-Dev] Cost-Free Slice into FromString constructors--Long

[Runar Petursson]

We've been talking this week about ideas for speeding up the parsing of
Longs coming out of files or network.  The use case is having a large string
with embeded Long's and parsing them to real longs.  One approach would be
to use a simple slice:
long(mystring[x:y])

an expensive operation in a tight loop.  The proposed solution is to add
further keyword arguments to Long (such as):

long(mystring, base=10, start=x, end=y)

The start/end would allow for negative indexes, as slices do, but otherwise
simply limit the scope of the parsing.  There are other solutions, using
buffer-like objects and such, but this seems like a simple win for anyone
parsing a lot of text.  I implemented it in a branch  runar-longslice-branch,
but it would need to be updated with Tim's latest improvements to long.
Then you may ask, why not do it for everything else parsing from string--to
which I say it should.  Thoughts?

-- 
Runar Petursson
Betur
runar at betur.net -- http://betur.net
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