From: Benoit Daloze <eregontp@...>
Date: 2009-12-11T02:42:30+09:00
Subject: Re: human-readable listing of array elements

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Hi,

As written in "Programming Ruby 1.9",
You can really use case as if ... elsif ... else ... end

So, in our case:

if self.size <= 1
  return self.to_s
elsif self.size == 2
  return self.join " #{conjunction} "
else
  array = self.dup
  array[-1] = [conjunction, array[-1]].join ' '
  array.join separator # proper English usage has comma before 'and'
end

becomes:

case
when self.size <= 1
  return self.to_s
when self.size == 2
  return self.join " #{conjunction} "
else
  array = self.dup
  array[-1] = [conjunction, array[-1]].join ' '
  array.join separator # proper English usage has comma before 'and'
end

Well, that's not especially better I think, but it looks cool and a little
less 'procedural' to me.

Anyway, I'm wondering how case manage the comma(,), is it acting like a OR
on each of the elements? I thought first to Array#=== but that isn't
defined. So, is it sort of syntactic sugar ?

2009/12/10 Robert Klemme <shortcutter@googlemail.com>

> 2009/12/10 Aldric Giacomoni <aldric@trevoke.net>:
> > Marnen Laibow-Koser wrote:
> >>
> >> Yes.  case won't handle <= conditions AFAIK.
> >
> > That is a very good point, though it does handle ranges, so "case 0..1"
> > would fit this particular scenario.
> > Your elsif statement is probably better suited here though.
>
> That point is not exactly true: while it doesn't out of the box, it
> can easily be made to:
>
> irb(main):001:0> ONE_OR_LESS = lambda {|n| n <= 1}
> => #<Proc:0x1014ed90@(irb):1 (lambda)>
> irb(main):002:0> class <<ONE_OR_LESS; alias === []; end
> => nil
> irb(main):003:0> 5.times {|i| case i; when ONE_OR_LESS then puts
> "yow!" else puts "nah" end}
> yow!
> yow!
> nah
> nah
> nah
> => 5
> irb(main):004:0>
>
> Apart from that, the length of an Array can as a minimum become only 0
> so the same test can be done as
>
> case array.size
> when 0,1 # <= 1
> ...
> when
> ...
> end
>
> Kind regards
>
> robert
>
> --
> remember.guy do |as, often| as.you_can - without end
> http://blog.rubybestpractices.com/
>
>

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