From: Adam Shelly <adam.shelly@...>
Date: 2008-02-29T05:42:26+09:00
Subject: Re: Named sprintf parameters

On 2/28/08, yermej <yermej@gmail.com> 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
> >
>
> However, when I try anything like that, it only calls the original
> method. The method defined inside of M isn't called.
...
>

I also couldn't get Ara's example to work, so I resorted to monkeypatching.
(Yes, I know, I am Destroying Ruby..)

----------

p "I am %s."  % "string"
p "I am %s."  % ["array"]
p "I am %s."  % { :name => "hash" }
begin
p "I am %(name)s." % { :name => "hash" }
rescue ArgumentError => err
 p "caught #{err}"
end

puts "\nMonkeyPatching!\n\n"
class String
  alias :old_percent :%
  def % arg
    arr = (arg.kind_of? Array) ? arg : [arg]
    target = self.gsub(/%\((.+?)\)/){|m|
      raise ArgumentError, "named parameters need hash" unless arg.kind_of? Hash
      arr << arg[$1.to_sym]
      "%#{arr.size}$"
    }
    target.old_percent arr
  end
end

p "I am %s."  % "string"
p "I am %s."  % ["array"]
p "I am %s."  % { :name => "hash" }
p "I am %(name)s." % { :name => "hash" }

p "I am %(name)s %(with)s %(what)s"%{:what => "multiple arguments",
        :with => "including", :name=> 'hash'}
p "I am %(name)s %(with)s %1$p"%{:with => "containing", :name=> 'hash'}
p "I am %(name)s." % [:name, "array"]


-Adam

P.S. It actually looks like patching sprintf wouldn't be too hard, as
long as you disallowed mixing named arguments with any other type.