Logic problem: need better logic for desired thruth table.

[Chris Angelico]

On Fri, May 29, 2015 at 8:53 PM, Tim Chase
<python.list at tim.thechases.com> wrote:
> On 2015-05-29 13:48, Chris Angelico wrote:
>> That said, though, using 0 for False and 1 for True is easily
>> the most common convention in use today, and the next most likely
>> case is that comparing booleans would give a simple and immediate
>> error. So it's most likely to be safe to do.
>
> There are popular exceptions though. coughshellscriptingcough

Yes, so you'd have to be careful if you port your complex script to
bash [1]. I'm also not sure how you'd even implement the comparison.
But shell scripting is still dwarfed by languages in which false is 0
and true is (usually) 1. Using Redmonk rankings:

1 JavaScript
2 Java
3 PHP
4 Python
5 C#
5 C++
5 Ruby
8 CSS
9 C
10 Objective-C
11 Perl
11 Shell

I'm not sure about Ruby, and I don't think CSS has a concept of
boolean arithmetic, but ten languages outrank shell scripting (Perl is
tied) and of them eight (maybe nine) use 0/1. Using langpop.com stats,
shell scripting comse up rather higher, but it's still beaten out -
and by considerable margins - by C, Java, PHP, JavaScript, C++, and
Python, all of which use 0/1. The Tiobe index seems to split up
several shells, which penalizes them severely (Bourne shell and bash
both come up in the 51-100 range), but even if they were merged,
they're unlikely to be able to nudge out the top five of Java, C, C++,
Objective-C, and C#. So while it's clearly false to state that 0/1 is
the _only_ convention in use today, it's fairly justifiably the _most
common_.

And of course, there are plenty of historical systems that were
different, as have been mentioned. But most programmers aren't going
to come across those... I hope!

ChrisA

[1] You'd also have to be insane. A bash script should not, in my
opinion, exceed about a page or two of code. I'm not sure how large a
bash script has to be before it collapses under its own gravity and
forms a black hole out of which no comprehension or sanity can escape,
but I'm taking no chances.