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To: python-list@python.org
From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: Puzzled by list-appending behavior
Date: Thu, 26 May 2011 14:44:52 -0400
References: <16c21256-48df-416a-971f-de49ca4cc981@x6g2000yqj.googlegroups.com> <201105261718.36646.akabaila@pcug.org.au>
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:6335

On 5/26/2011 3:18 AM, Algis Kabaila wrote:

> And why do you insist on calling an instance of list, "list"? Even a
> human reader will confuse which is which. What you are showing is an
> example how confusing things become when a keyword (list) is
> over-written (with list instance).

(Minor note: 'list' is not a keyword (if it were, it could not be 
over-ridden) but it is a builtin.) You are correct, it is confusing. 
Such usage will also lead to bugs if one ever tries to access the class 
as 'list' later in the program.

Here is a legitimate usage of builtins masking:

import builtins
def list(iterable):
     print('building list from {}: {}'.format(type(iterable),iterable))
     return builtins.list(iterable)

a = list((1,2,3))
b = list({1,2,3})
###
building list from <class 'tuple'>: (1, 2, 3)
building list from <class 'set'>: {1, 2, 3}

-- 
Terry Jan Reedy