Path: csiph.com!usenet.pasdenom.info!news.albasani.net!newsfeed.freenet.ag!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
To: python-list@python.org
From: Dennis Lee Bieber <wlfraed@ix.netcom.com>
Subject: Re: Python Newbie
Date: Sat, 23 Feb 2013 13:29:27 -0500
Organization: > Bestiaria Support Staff <
References: <mailman.2237.1361508661.2939.python-list@python.org> <kg7mfi$8oh$1@dont-email.me> <mailman.2259.1361535166.2939.python-list@python.org> <kg7t19$a63$1@dont-email.me> <XnsA16F92E78A66duncanbooth@127.0.0.1> <5127848B.1060004@gmail.com> <mailman.2271.1361545569.2939.python-list@python.org> <928d2cf7-728b-4f35-b8c9-4c9b958507e5@googlegroups.com> <mailman.2309.1361573184.2939.python-list@python.org> <8eadd52c-d533-4333-8c7f-7bf3a6d7b046@googlegroups.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Precedence: list
Newsgroups: comp.lang.python
Message-ID: <mailman.2364.1361644177.2939.python-list@python.org>
Lines: 46
NNTP-Posting-Host: 2001:888:2000:d::a6
Xref: csiph.com comp.lang.python:39694

On Fri, 22 Feb 2013 15:38:53 -0800 (PST), piterrr.dolinski@gmail.com
declaimed the following in gmane.comp.python.general:


> if (some statement):            # short form
> 
> in the example I gave, but you figured exactly what I mean. Of course if the condition (some statement) is boolean there is no point adding "== true" or similar. But if (some statement) represents a value this is where I have trouble and again the origins of this date back to when Python had no boolean type. So now at least I understand it.
>

	Python isn't the only language that will treat non-Boolean as
Boolean, though applying it to strings, floats, other objects may be an
extension (and one which does simplify a lot of code, in my view).

	Error codes under DEC VAX/VMS used odd integers for
"success/information" and even integers for "warning/error" (been too
many years, I think positive integers were success/warning, negative
integers were information/error; I could also be wrong on which set were
even... if 0 were no-info/success then odd were errors and even were
success)).

	The VAX instruction set only used the least significant bit for
Boolean checks, so one could do a fast check by 

	if (retCode) then
		#assume odd are errors
		#examine for "correctible" error codes
		#or dump an exception
	else
		#assume we don't care for specific info messages
		#a la: tape already at beginning, if the operation was a rewind
		#do normal processing
	end if


> Btw, there are still languages with no boolean type today, MySQL for one. This creates big efficiency problems when fetching data from the database into a C# program - what should be a bool is fetched as an 8-byte integer! But that's a different story. I shut up now.
> 

	SQL itself did not define a Boolean type until the 1999 standard --
and in that standard, Boolean is an optional feature.
http://en.wikipedia.org/wiki/Boolean_data_type#SQL

	Apparently few database engines implement a true Boolean.
-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
        wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/