Thanks! This is a very interesting idea, I'd like to keep this around somehow.
I also see that you noticed a problem with text I/O in the current design; there's no easy way to implement readline() efficiently. I want readline() to be as efficient as possible -- "for line in <file>" should *scream*, like it does in 2.x. --Guido On 3/10/07, Mark Russell <[EMAIL PROTECTED]> wrote: > As an experiment with the new IO library (http://docs.google.com/Doc? > id=dfksfvqd_1cn5g5m), I added support for walking through the lines > of a file backwards using the reversed() iterator: > > for line in reversed(open(path)): > ... > > It works by scanning backwards through the file a block at a time > (using seek()) but will handle arbitrary length lines. > > The patch is at http://www.python.org/sf/1677872. The code is > currently directly in Lib/io.py, but in fact the only internal access > it needs is adding the __reversed__ hook to TextIOWrapper. > > It's useful for scanning backwards through large log files, but it's > also IMHO a nice example of the benefits of the new library. The > version of this that I used under python 2.5 had to use os.seek() etc > on file descriptors, whereas now it just wraps a new buffering class > (io.TextLineReverser) around the raw IO object. Among other things > it makes unit tests simpler - instead of messing around with > temporary files the tests can do things like: > > b = io.BytesIO(b'one\ntwo\nthree\n') > assert list(io.TextLineReverser(b)) == [ 'three\n', 'two\n', 'one > \n' ] > > Mark Russell > > _______________________________________________ > Python-3000 mailing list > Python-3000@python.org > http://mail.python.org/mailman/listinfo/python-3000 > Unsubscribe: > http://mail.python.org/mailman/options/python-3000/guido%40python.org > -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-3000 mailing list Python-3000@python.org http://mail.python.org/mailman/listinfo/python-3000 Unsubscribe: http://mail.python.org/mailman/options/python-3000/archive%40mail-archive.com
