[Python-Dev] str object going in Py3K (original) (raw)

Walter Dörwald walter at livinglogic.de
Thu Feb 16 18:14:45 CET 2006

Bengt Richter wrote:

On Wed, 15 Feb 2006 18:57:26 -0800, Guido van Rossum <guido at python.org> wrote:

[...] My expectation is that the Py3k standard I/O library will do all of its own conversions on top of binary files anyway -- if you missed it, I'd like to get rid of any ties to C's stdio. Would the standard I/O module have low level utility stream-processing generators to do things like linesep normalization in text or splitlines etc? I.e., primitives that could be composed for unforseen usefulness, like unix pipeable stuff? Maybe they could even be composable with '|' for unixy left->right piping, e.g., on windows for line in (os.open('somepath') | linechunker | decoder('latin-1')): ... where os.open('path').or(linechunker) returns linechunker(os.open('path')), which in turn has an or to do similarly. Just had this bf, but ISTM it reads ok. The equivalent nested generator expression with same assumed primitives would I guess be for line in decoder('latin-1')(linechunker(binaryfile('path'))): ... which doesn't have the same natural left to right reading order to match processing order.

I'm currently implementing something like this, which might go into IPython. See http://styx.livinglogic.de/~walter/IPython/ipipe.py for code. (This requires the current IPython svn trunk)

Examples:

for f in ils("/usr/lib/python2.3/") | ifilter("name.endswith('.py')"): print f.name, f.size

for p in ipwd | ifilter("shell=='/bin/false'") | isort("uid") |
ieval('"%s (%s)" % (_.name, _.gecos)'): print p

The other part of the project is a curses based browser for the output of these pipelines. See http://styx.livinglogic.de/~walter/IPython/newdir.gif for a screenshot of the result of ils("/usr/lib/python2.3/") | ifilter("name.endswith('.py')")

Bye, Walter Dörwald

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