Bugs item #1569057, was opened at 2006-10-01 23:49
Message generated for change (Comment added) made by rainy
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1569057&group_id=5470
Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
>Category: Documentation
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Submitted By: andrei kulakov (rainy)
Assigned to: Nobody/Anonymous (nobody)
Summary: Using .next() on file open in write mode writes junk to file
Initial Comment:
When you open a file in write mode and use .next(), it
prints an error and writes many lines of junk to file.
I tested on windows and python 2.5:
>>> f = open('test', 'w')
>>> f.fileno()
4
>>> f.write('1\n')
>>> f.write('2\n3\n4\n')
>>> f.next()
Traceback (most recent call last):
File "<pyshell#8>", line 1, in <module>
f.next()
IOError: [Errno 9] Bad file descriptor
>>> f.close()
>>> f = open('test')
>>> f.next()
'1\n'
>>> f.next()
'2\n'
>>> f.next()
'3\n'
>>> f.next()
'4\n'
>>> f.next()
'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x
00\x00\x00\x00\x00\x
00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
\x00\x00\x00\x00\x00\
x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
\x00\x00\x00
...many more lines of junk...'
----------------------------------------------------------------------
>Comment By: andrei kulakov (rainy)
Date: 2006-10-03 20:23
Message:
Logged In: YES
user_id=511010
Python newsgroup folks said that this is normal because when
switching between write/read modes without doing flush()
first, result is undefined. There was a suggestion from
Terry Ready to add this to documentation on file methods:
"When switching from reading or writing (or vice versa),
call flush(), or
the result will be undefined."
thx, -andrei
----------------------------------------------------------------------
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1569057&group_id=5470
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
