[Python-Dev] Python Documentation Problem Example

xah lee xah at xahlee.org
Sun Apr 1 17:39:04 CEST 2007

Python Doc Problem Example: os.path.split()

Xah Lee, 20050918

Quote from: http://www.python.org/doc/2.4.1/lib/module-os.path.html

     Split the pathname path into a pair, (head, tail) where tail is  
the last pathname component and head is everything leading up to  
that. The tail part will never contain a slash; if path ends in a  
slash, tail will be empty. If there is no slash in path, head will be  
empty. If path is empty, both head and tail are empty. Trailing  
slashes are stripped from head unless it is the root (one or more  
slashes only). In nearly all cases, join(head, tail) equals path (the  
only exception being when there were multiple slashes separating head  
from tail).

This confusive verbiage is a result of the author's pretention in a  
austere style and his failure to think clearly before writing.

Suggested rewrite:

     returns a pair (dirname,filename), where dirname is the part of  
path up to the last slash, and filename is the rest of the string  
after the last slash.

     Exceptional cases are:
     • if path is a single slash (or repeated), then path == dirname  
and filename is empty.
     • If the last slash is repeated, they are treated as one single  

I was working on a program where i needed to split a path into  
dirname, corename, and suffix.

I came to this page and took me a while to understand what split() is  
about. There are other path related functions splitext(), splitdrive 
(), basename(), dirname(). User has to scan the whole page and read  
painfully each one to fully understand how to choose and use them for  
the task at hand.

As i have explained before (see references at bottom), documentation  
should be organized oriented towards programer's tasks, not  
alphabetically, compiler view, or computer sciency scheme. On this  
os.path module, split(), splittext(), dirname(), basename() should  
all be under one section. This way, their usefulness and each's  
fitness becomes clearer, and also easier to document as a collective.  
Other functions that test files or get info about files should be  
grouped together. Don't be afraid of having functions that won't fit  
into some grouping scheme. For exapmle, the walk() and  
supports_unicode_filenames() can be lumped at the bottom as Other.  
The need to present materials in some aloof, computer sciency,  
academic, technically precise way is a major usability problem of the  
Python doc.

(the Pythoners's need to present materials in a formal style is a  
backlash of the happy-go-lucky sloppiness of unix/perl community.  
However, they being pretty much the same crowd without significant  
critical thinking and writing skills, cannot do better by hiding in  

Also, at the top we see:

     Warning: On Windows, many of these functions do not properly  
support UNC pathnames. splitunc() and ismount() do handle them  

As indicated before, this is a exhibition of tech geeking and  
jargonizing. If this warning is necessary, place it at the bottom of  
the page as a footnote. Also, spell out UNC, and provide a link to  
its proper spec.

Tech geekers are very pretentious and cryptic in their tech docs.  
They are afraid, as if spelling out UNC would make them  
unprofessional, that their peers would deem them inferior. There are  
a myriad of technical standards that any programer could only be  
familiar with a fraction, confined to his area of expertise.  
Standards and its acronyms come and go, and each with varying degrees  
of precision, actual relevance, and they are intermingled with de  
facto practices in the commercial world that may not even have  
official names. The tech geekers are clouded by their tech-expertise.  
The purpose of documentation is not some cold academic presentation.  
Vast majority who came to use os.path wouldn't know what UNC is nor  
do they need to know. Spell things out when in doubt.

UNC here, isn't really a significant “standard”. This warning  
should be left out.


     * Regroup path manipulating functions together, file info  
functions together, etc.
     * After regrouping the functions, much of the writing can be  
simplified since these functions are doing similar tasks. Writing can  
focus on their differences. Rewrite them with a focus on what users  
needs to do. Add examples in intricate situations. Avoid the computer  
science thesis writing style.
     * Remove the UNC warning at the top.

Here are a few other Python doc problems i've written in the past years:

Python doc problem example: os.system()

Python Doc Problem Example: os.path.split()

Python Doc Problem Example: sort()

Python Doc Problem Example: gzip module

   xah at xahlee.orghttp://xahlee.org/

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