From: Brian Candler <B.Candler@...>
Date: 2007-03-01T05:13:23+09:00
Subject: Re: Ruby's "case" doesn't behave like a normal switch

On Thu, Mar 01, 2007 at 04:36:39AM +0900, Pit Capitain wrote:
> gga schrieb:
> >For completeness sake, you can also emulate C's lack of a break;
> >statement in ruby by doing redo/retry, like:
> >
> >a = 1
> >
> >catch(:redo) do
> >  case a
> >  when 1
> >    print '1'
> >    a = 2
> >    redo
> >  when 2
> >    puts 'and 2'
> >  end
> >end
> >
> >This makes ruby's case statement probably the best of any language.
> 
> I didn't know the "catch(:redo)". Is this documented somewhere?

'redo' is documented at
http://www.rubycentral.com/book/tut_expressions.html

'catch' is documented at
http://www.rubycentral.com/book/tut_exceptions.html

However they're not a pair, and I don't think that 'catch' does anything in
particular in the above example, apart from causing the block to be executed
once. You could achieve the same with:

a = 1
1.times do
  case a
  when 1
    print '1'
    a = 2
    redo
  when 2
    puts 'and 2'
  end
end

Or:

a = 1
begin
  case a
  when 1
    print '1'
    a = 2
    redo
  when 2
    puts 'and 2'
  end
end while false

Regards,

Brian.