[ python-Bugs-1278906 ] invalid syntax in os.walk() first example

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Bugs item #1278906, was opened at 2005-09-01 06:55
Message generated for change (Comment added) made by rhettinger
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Category: Documentation
Group: Python 2.5
>Status: Closed
>Resolution: Works For Me
Priority: 5
Submitted By: YoHell (yohell)
Assigned to: Nobody/Anonymous (nobody)
Summary: invalid syntax in os.walk() first example

Initial Comment:
Hi!

The first example code block in the documentation for
os.walk() has invalid syntax in it.

The docs are available here:
http://www.python.org/doc/current/lib/os-file-dir.html#l2h-1466

This is the example code block:
import os
from os.path import join, getsize
for root, dirs, files in os.walk('python/Lib/email'):
    print root, "consumes",
    print sum(getsize(join(root, name)) for name in files),
    print "bytes in", len(files), "non-directory files"
    if 'CVS' in dirs:
        dirs.remove('CVS')  # don't visit CVS directories

Line 5 has the the invalid syntax:
    print sum(getsize(join(root, name)) for name in files),

The example works if brackets are added like so:
    print sum([getsize(join(root, name)) for name in
files]),

I recommend that someone responsible should make this
update in the docs.

You guys are brilliant. Thanks for a splendid language
with docs to match! 

Cheers!

/Joel Hedlund
PhD student, 
IFM Bioinfomatics, Linköping University

----------------------------------------------------------------------

>Comment By: Raymond Hettinger (rhettinger)
Date: 2005-09-01 07:44

Message:
Logged In: YES 
user_id=80475

I suspect you are using Py2.4 documentation while running
Py2.3 or earlier.  In Py2.4, the bracketless syntax was
introduced with new semantics which produce a similar result
but run with a generator instead of a list comprehension,
resulting in a significant savings in memory.



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