Terry J. Reedy added the comment: The help(linecache) Description is more specific as to the intention (based on traceback usage): "This is intended to read lines from modules imported -- hence if a filename is not found, it will look down the module search path for a file by that name." My experiments show that this is too specific. It *can* read any file that it can find and decode as utf-8 (default, or you say, locale encoding or coding in cookie line). Find = absolute path

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linecache.getline('c:/programs/pydev/py32/LICENSE', 1) 'A. HISTORY OF THE SOFTWARE\n'

or relative path on sys.path

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linecache.getline('idlelib/ChangeLog', 1) 'Please refer to the IDLEfork and IDLE CVS repositories for\n' linecache.getline('idlelib/extend.txt', 1) 'Writing an IDLE extension\n'

Decode fails on byte illegal for utf-8:

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linecache.getline('idlelib/CREDITS.txt', 1) UnicodeDecodeError: 'utf8' codec can't decode byte 0xf6 in position 1566: invalid start byte

(It reads and decodes entire file even though only line 1 was requested. It choked on Löwis. I believe Py3 distributed text files should be utf-8 instead of latin-1.) If I got rules right, doc should say "Filename must be an absolute path or relative path that can be found on sys.path." and "File must be utf-8 encoded or locale encoded or a Python file with a coding cookie." (If you tried /etc/passwd, how did it fail?) ---------- nosy: +terry.reedy _______________________________________ Python tracker http://bugs.python.org/issue11726 _______________________________________

Changes by Terry J. Reedy : ---------- versions: -Python 3.1 _______________________________________ Python tracker http://bugs.python.org/issue11726 _______________________________________

Thomas Kluyver added the comment: Someone on reddit ran into this, expecting that linecache can be used for an arbitrary text file: http://www.reddit.com/r/Python/comments/2yetxc/utf8_encoding_problems/ I was quite surprised that the docs say "allows one to get any line from any file." I've always understood that linecache is specifically for Python files, and the use of tokenize.open() means that it will only work for files that are UTF-8 or have the #coding: magic comment in the first two lines. I think the docs should at least mention this; I'm happy to work on a patch for it at some point if people agree. ---------- nosy: +takluyver _______________________________________ Python tracker http://bugs.python.org/issue11726 _______________________________________

Thomas Kluyver added the comment: First attempt at describing this attached. ---------- keywords: +patch Added file: http://bugs.python.org/file38424/linecache-encoding-doc.patch _______________________________________ Python tracker http://bugs.python.org/issue11726 _______________________________________

Roundup Robot added the comment: New changeset 51341af466e3 by Victor Stinner in branch '3.4': Issue #11726: clarify linecache doc: linecache is written to cache Python https://hg.python.org/cpython/rev/51341af466e3 ---------- nosy: +python-dev _______________________________________ Python tracker http://bugs.python.org/issue11726 _______________________________________

STINNER Victor added the comment: 4 years to fix this minor documentation issue, I feel ashamed... ---------- resolution: -> fixed status: open -> closed _______________________________________ Python tracker http://bugs.python.org/issue11726 _______________________________________

R. David Murray added the comment: OK, on further investigation I guess it wasn't intended to be so general :) But I still think we should make a nod to the reality that it can be used on other text files. I'll re-close the issue but I may add a sentence to the docs. ---------- status: open -> closed _______________________________________ Python tracker http://bugs.python.org/issue11726 _______________________________________

Antti Haapala added the comment: Every now and then there are new questions and answers regarding the use of `linecache` module on Stack Overflow for doing random access to text files, even though the documentation states that it is meant for Python source code files. One problem is that the title still states: "11.9. linecache — Random access to text lines"; the title should really be changed to "Random access to Python source code lines" so that the title wouldn't imply that this is a general-purpose random access library for text files. ---------- nosy: +ztane _______________________________________ Python tracker http://bugs.python.org/issue11726 _______________________________________