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Date: Fri, 15 Jul 2011 20:38:08 +1000
From: Cameron Simpson <cs@zip.com.au>
To: Steven D'Aprano <steve+comp.lang.python@pearwood.info>
Subject: Re: None versus MISSING sentinel -- request for design feedback
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On 15Jul2011 20:17, Steven D'Aprano <steve+comp.lang.python@pearwood.info> wrote:
| Cameron Simpson wrote:
| > I suppose there's no scope for having the append-to-the-list step sanity
| > check for the sentinel (be it None or otherwise)?
| 
| It is not my responsibility to validate data during construction, only to do
| the right thing when given that data. The right thing being, raise an
| exception if values are not numeric, unless an explicit "missing" value
| (whatever that ends up being).

Well there you go. You need to use MISSING, not None. As you say, None
can easily be a mistake and you want to be sure. If what you describe as
"right" is right, then I too would be using a special sentinal instead
of None.
-- 
Cameron Simpson <cs@zip.com.au> DoD#743
http://www.cskk.ezoshosting.com/cs/

The English language has a word to describe a group of anarcho-collectivists
without resorting to spiffy hyphenated coined phrases: a mob.
        - Tim Mefford, <tim@physics.orst.edu>