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From: Bart <bc@freeuk.com>
Newsgroups: comp.lang.c
Subject: Re: else ladders practice
Date: Wed, 6 Nov 2024 10:01:16 +0000
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On 06/11/2024 07:26, Kaz Kylheku wrote:
> On 2024-11-05, Bart <bc@freeuk.com> wrote:

>> Well, it started off as 2-way select, meaning constructs like this:
>>
>>      x = c ? a : b;
>>      x := (c | a | b)
>>
>> Where one of two branches is evaluated. I extended the latter to N-way
>> select:
>>
>>      x := (n | a, b, c, ... | z)
> 
> This looks quite error-prone. You have to count carefully that
> the cases match the intended values. If an entry is
> inserted, all the remaining ones shift to a higher value.
> 
> You've basically taken a case construct and auto-generated
> the labels starting from 1.

It's a version of Algol68's case construct:

    x := CASE n IN a, b, c OUT z ESAC

which also has the same compact form I use. I only use the compact 
version because n is usually small, and it is intended to be used within 
an expression: print (n | "One", "Two", "Three" | "Other").

This an actual example (from my first scripting language; not written by 
me):

      Crd[i].z := (BendAssen |P.x, P.y, P.z)

An out-of-bounds index yields 'void' (via a '| void' part inserted by 
the compiler). This is one of my examples from that era:

   xt := (messa | 1,1,1, 2,2,2, 3,3,3)
   yt := (messa | 3,2,1, 3,2,1, 3,2,1)

Algol68 didn't have 'switch', but I do, as well as a separate 
case...esac statement that is more general. Those are better for 
multi-line constructs.

As for being error prone because values can get out of step, so is a 
function call like this:

    f(a, b, c, d, e)

But I also have keyword arguments.