Runar Petursson wrote: > 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?
-1 This is a somewhat specialized parsing application and should not be allowed to muck-up an otherwise simple, general-purpose API. Micro-optimizations do not warrant API changes. Certainly, it should not be propogated to everything that can parse from a string. Also, you are likely to find that the cost of varargs and kwargs will offset the slicing gains. I think the whole notion is off base. The int(mystring[x:y]) situation is only important when you're doing it many times. Often, you'll be doing other conversions as well. So, you would be better-off creating a text version of the struct module that would enable you to extract and convert many elements from a long record stored as text. Alternately, you could expose a function styled after fscanf(). IOW, better to provide to general purpose text parsing tool than to muck-up the whole language for one specialized application. Raymond _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
