From: Pit Capitain <pit@...>
Date: 2002-07-10T19:16:24+09:00
Subject: Re: Case expressions and LHS of assignment....

On 10 Jul 2002, at 19:01, Hugh Sasse Staff Elec Eng wrote:

> On Wed, 10 Jul 2002, Peter Hickman wrote:
> 
> > Perhaps you could use an array to hold you instance variables rather
> > than the 3 seperate ones. This then gives
> >
> > def initialize
> >      @values = Array.new
> >     (1..3).times { @value << "Initial" }
> > end
> >
> > def assign(x,y)
> >     @values[x] = y
> > end
> >
> > Even shorter (especially without error checking :-) ) and much much
> > clearer.
> 
> You're taking the contrived, cut-down example too literally :-).  The
> numbers were easier to type to test this out,  I was using symbols in
> fact, :x, :y, and :z  in the first place, but the problem is more
> general than that because a case statement can be used with anything
> that copes with ===.

You can still use a similar approach using a hash with symbols as 
keys. In the assignment, use the case expression to detemine the 
key. Something like

def initialize
  @values = Hash.new( "Initial" )
end

def assign( x, y )
  @values[
    case x
    when ...
      :x
    when ...
      :y
    else
      :z
    end
  ] = y
end

Regards,
Pit