"Don't rebind built-in names*" - it confuses readers

From	Terry Jan Reedy <tjreedy@udel.edu>
Subject	"Don't rebind built-in names*" - it confuses readers
Date	2013-06-10 20:14 -0400
Newsgroups	comp.lang.python
Message-ID	<mailman.3001.1370909708.3114.python-list@python.org> (permalink)

Show all headers | View raw

Many long-time posters have advised "Don't rebind built-in names*.

* Unless you really mean to mask it, or more likely wrap it, such as 
wrapping print to modify some aspect of its operation than one cannot do 
with its keyword parameters. The point for this post is that such 
wrapping modify or extend the basic meaning of the builtin, but do not 
abolish it.

Reasons have been given in various related forms: 'my long experience 
tells me its bad', 'you may need the builtin later', 'you may forget 
that you rebound the builtin, 'it can lead to subtle bugs, etc.

Leaving aside the code writer and code operation, I recently discovered 
that it is not nice for readers, whether humans or programs.

For instance, open Lib/idlelib/GrepDialog.py in an editor that colorizes 
Python syntax, such as Idle's editor, jump down to the bottom and read 
up, and (until it is patched) find
                     list.append(fn)
with 'list' colored as a builtin. Stop. That looks wrong. List.append 
needs two arguments: a list instance and an object to append to the 
list. The 'solution' is in a previous line
         list = []
Reading further, one sees that the function works with two lists, a list 
of file names, unfortunately called 'list', and a list of 
subdirectories, more sensibly call 'subdirs'. I was initially confused 
and reading the code still takes a small bit of extra mental energy. 
Idle stays confused and will wrongly color the list instance name until 
it is changed. Calling the file list 'fnames' or 'filenames' would have 
been clearer to both me and Idle.

--
Terry Jan Reedy

Back to comp.lang.python | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

"Don't rebind built-in names*" - it confuses readers Terry Jan Reedy <tjreedy@udel.edu> - 2013-06-10 20:14 -0400
  Re: "Don't rebind built-in names*" - it confuses readers rusi <rustompmody@gmail.com> - 2013-06-10 19:36 -0700
    Re: "Don't rebind built-in names*" - it confuses readers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-11 03:02 +0000
      Re: "Don't rebind built-in names*" - it confuses readers rusi <rustompmody@gmail.com> - 2013-06-10 20:30 -0700
        Re: "Don't rebind built-in names*" - it confuses readers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-11 05:52 +0000
        Re: "Don't rebind built-in names*" - it confuses readers Chris Angelico <rosuav@gmail.com> - 2013-06-11 17:20 +1000
      Re: "Don't rebind built-in names*" - it confuses readers Chris Angelico <rosuav@gmail.com> - 2013-06-11 13:57 +1000
      Re: "Don't rebind built-in names*" - it confuses readers Serhiy Storchaka <storchaka@gmail.com> - 2013-06-11 18:55 +0300
      Re: "Don't rebind built-in names*" - it confuses readers Mark Janssen <dreamingforward@gmail.com> - 2013-06-12 17:04 -0700
        Re: "Don't rebind built-in names*" - it confuses readers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 01:01 +0000
      Re: "Don't rebind built-in names*" - it confuses readers Chris Angelico <rosuav@gmail.com> - 2013-06-13 10:08 +1000
        Re: "Don't rebind built-in names*" - it confuses readers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 01:08 +0000
          Re: "Don't rebind built-in names*" - it confuses readers Chris Angelico <rosuav@gmail.com> - 2013-06-13 11:30 +1000
      Re: "Don't rebind built-in names*" - it confuses readers Skip Montanaro <skip@pobox.com> - 2013-06-12 19:18 -0500
      Re: "Don't rebind built-in names*" - it confuses readers Chris Angelico <rosuav@gmail.com> - 2013-06-13 10:33 +1000
      Re: "Don't rebind built-in names*" - it confuses readers Ethan Furman <ethan@stoneleaf.us> - 2013-06-12 17:30 -0700
  Re: "Don't rebind built-in names*" - it confuses readers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-11 02:56 +0000
    Re: "Don't rebind built-in names*" - it confuses readers Terry Jan Reedy <tjreedy@udel.edu> - 2013-06-11 02:06 -0400
    Re: "Don't rebind built-in names*" - it confuses readers Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-11 08:22 -0700
      Re: "Don't rebind built-in names*" - it confuses readers Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-11 16:59 +0000
      Re: "Don't rebind built-in names*" - it confuses readers Chris Angelico <rosuav@gmail.com> - 2013-06-12 03:32 +1000

csiph-web