From: Trans <transfire@...>
Date: 2008-03-02T23:15:49+09:00
Subject: Re: Named sprintf parameters



On Feb 28, 7:13 pm, ara howard <ara.t.how...@gmail.com> wrote:
> On Feb 28, 2008, at 1:09 PM, yermej wrote:
>
>
>
> > On Feb 28, 11:29 am, ara howard <ara.t.how...@gmail.com> wrote:
>
> >> class String
> >>   module M
> >>     def % *args
> >>       newstuff
> >>       super
> >>     end
> >>   end
> >>   include M
> >> end
>
> > Can you please explain this? It looks to me like it would allow you to
> > override a method, but still call the original without using alias.
> > However, when I try anything like that, it only calls the original
> > method. The method defined inside of M isn't called. Is that a 1.9
> > thing or am I misunderstanding what you meant?
>
> i was just being stupid.  you'd need something like this
>
> cfp2:~ > cat a.rb
> class String
>
>    Percent = instance_method '%' unless defined? Percent
>
>    def % *a, &b
>      a.flatten!
>      string =
>        case a.last
>          when Hash
>            expand a.pop
>          else
>            self
>        end
>      if a.empty?
>        string
>      else
>        Percent.bind(string).call(*a, &b)
>      end
>    end
>
>    def expand! vars = {}
>      loop do
>        changed = false
>        vars.each do |var, value|
>          var = var.to_s
>          var.gsub! %r/[^a-zA-Z0-9_]/, ''
>          [
>            %r/\$#{ var }\b/,
>            %r/\@#{ var }\b/,
>            %r/\$\{\s*#{ var }\s*\}/,
>            %r/\@\{\s*#{ var }\s*\}/,
>          ].each do |pat|
>            changed = gsub! pat, "#{ value }"
>          end
>        end
>        break unless changed
>      end
>      self
>    end
>
>    def expand opts = {}
>      dup.expand! opts
>    end
>
> end
>
> puts( 'I am @name'.expand(:name => 'Ara') )
> puts( 'I am @name' % {:name => 'Ara'} )
>
> cfp2:~ > ruby a.rb
> I am Ara
> I am Ara

Hmmm... this looks more like an answer to the interpolation question
asked in a earlier thread. Is this a full-fledge implementation? Would
it be a better solution then:

  def String.interpolate(&str)
    eval "%{#{str.call}}", str.binding
  end

T.