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
--
http://mail.python.org/mailman/listinfo/python-list
