From: Glenn Jackman <glennj@...>
Date: 2009-08-14T03:00:16+09:00
Subject: Re: Assignment from within a block?

At 2009-08-13 07:23AM, "Gerald Ebberink" wrote:
>  On Thu, 2009-08-13 at 09:37 +0000, Glenn Jackman wrote:
>  
> > At 2009-08-13 03:54AM, "Gerald Ebberink" wrote:
> > >  require 'bigdecimal'
> > >  
> > >  var1 = 10
> > >  var2 = 20
> > >  ["var1","var2"].each do |v|
> > >  v = BigDecimal.new(v.to_s)
> > >  end
> > >  var1.class
> > >  
> > >  Why isn't var1 changed, and how do I get the behaviour I want (and this
> > >  is ofcourse not for just to vars)
> > 
> > I suspect you want
> >     
> >     var1, var2 = [var1, var2].collect {|v| BigDecimal.new(v.to_s)}
> >     
> >     [var1,var2].collect {|v| v.class}  # => [BigDecimal, BigDecimal]
>  
>  
>  Yes this would be the preferred solution if I would know which vars
>  would be in the array.  But the array is filled during operation and
>  of arbitrary length (not nil).

I wondered why you had an array of strings.  You just need to eval the
variable name string.

    bigs = variable_names.collect {|v| BigDecimal.new(eval(v).to_s)}

If you're creating the BigDecimal objects in a different context than
where the variables exist, you need to obtain that context:

    var1, var2 = 10,20

    def convert_to_big(varnames, context)
      # local variables "var1" and "var2" don't exist here
      # but they are in the binding "context"
      varnames.collect {|v| BigDecimal.new(eval(v, context).to_s)}
    end

    bigs = convert_to_big(["var1", "var2"], binding)


-- 
Glenn Jackman
    Write a wise saying and your name will live forever. -- Anonymous