[Python-bugs-list] [ python-Bugs-487277 ] Different behavior of readline()

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Bugs item #487277, was opened at 2001-11-29 14:43
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Category: Python Interpreter Core
Group: Python 2.2
Status: Open
Resolution: None
Priority: 5
Submitted By: Gustavo Niemeyer (niemeyer)
Assigned to: Nobody/Anonymous (nobody)
Summary: Different behavior of readline()

Initial Comment:
The behavior of readline() has changed on 2.2. This 
should be documented.

Example:

Python 2.1 (#1, Jun 22 2001, 17:13:13)
[GCC 2.95.3 20010315 (release) (conectiva)] on 
linux-i386
Type "copyright", "credits" or "license" for more 
information.
>>> open("/etc").readline()
''

Python 2.2b2+ (#1, Nov 27 2001, 21:39:35)
[GCC 2.95.3 20010315 (release) (conectiva)] on 
linux-ppc
Type "help", "copyright", "credits" or "license" for 
more information.
>>> open("/etc").readline()
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
IOError: [Errno 21] Is a directory



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>Comment By: Martin v. Löwis (loewis)
Date: 2001-11-30 01:19

Message:
Logged In: YES 
user_id=21627

Any change is user-visible: for any change, I can construct
a program that behaves differently with the change.
Otherwise, the change would be useless (except that it may
add commentary or some such).

In fact, the change *is* documented, namely in the CVS log.
Extracting all those fragments into a single document would
be  time-consuming and pointless: nobody can read through
hundreds of changes.

Your program would have blown up even if there was such a
document. If a change has severe effects on many existing
programs, it should be implemented differently.

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Comment By: Gustavo Niemeyer (niemeyer)
Date: 2001-11-29 16:10

Message:
Logged In: YES 
user_id=7887

I think *any* change visible at user space should be 
documented. I discovered this change because a program I 
have never read in my life (in fact, I didn't even know it
was written in python) has blown up in my hands. It was
reading files and safely ignoring directories by testing
readline()'s output.



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Comment By: Martin v. Löwis (loewis)
Date: 2001-11-29 15:53

Message:
Logged In: YES 
user_id=21627

I don't think this needs to be documented. The change is a
bug fix, reading from a directory was never supposed to work
(whether in lines or not).

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

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http://sourceforge.net/tracker/?func=detail&atid=105470&aid=487277&group_id=5470