From: Leslie Viljoen <leslie@...>
Date: 2005-11-24T05:37:34+09:00
Subject: Re: syntax error warning: useless use of a variable in void context

Tom Reilly wrote:

> class Tl
>    def initialize(a,b)
>        @a = a
>        @b = b
>    end
>       def to_s
>        "#{@a}    #{@b}"
>    end
>       def <=>(tlr)
>        if @a > tlr.@a
>            1
>        elsif
>            @a == tlr.@a
>                0
>        else
>            -1
>        end
>    end
>    end
>
> aa = Tl.new("tom","reilly")
> ab = Tl.new("jack","charity")
>
> r = aa <=> ab
> p r
>
> --------------------------
> >ruby -cw tmp.rb
> tmp.rb:12: syntax error
> tmp.rb:12: warning: useless use of a variable in void context
> tmp.rb:14: syntax error
> tmp.rb:15: syntax error
> tmp.rb:15: warning: useless use of a variable in void context
> tmp.rb:19: warning: else without rescue is useless
> tmp.rb:22: syntax error
> >Exit code: 1
>
>
> Considering I've been using Ruby for a couple of years, I've been 
> totally frustrated
> making this bit of code work.
>
> Help!
> Thanks

You seem to be having difficulty accessing the variables in the tla object.
This seems to work:

#!/usr/bin/env ruby

class Tl
   attr_reader :a, :b

   def initialize(a,b)
       @a = a
       @b = b
   end

   def to_s
       "#{@a}    #{@b}"
   end

   def <=>(tlr)
       if @a > tlr.a
           1
       elsif
           @a == tlr.a
               0
       else
           -1
       end
   end
end

aa = Tl.new("tom","reilly")
ab = Tl.new("jack","charity")

r = aa <=> ab
p r