From: GOTO Kentaro <gotoken@...>
Date: 2002-09-25T19:14:50+09:00
Subject: Re: are functions/methods "first class objects"?

At Wed, 25 Sep 2002 15:59:02 +0900,
Bulat Ziganshin wrote:
> hmm. you don't understand. sort string is a sequence of chars, which
> maps to sort criterions. this char may be

oops. I didn't read context :<

> e for extennsion
> n for filename w/o path/extension
> s for size
> g for group (one group is c sources, next - executables and so on)
> i for some intellectual THING :)
> 
> i need to translate sequence of this chars to function which returns
> array with all the data for sort_by:
> 
> sort_files "es"
> sort_files "en"
> sort_files "geis"
> 
> and much more variants. so i need to construct closure on the fly

I see.  A point seems how to pass a filename to each component...

  class Proc
    def *(other) lambda{|i| other.yield(self.yield(i))} end
  end

  F_Bootstrap = Proc.new{|i| [i, []]}
  F_SIZE = Proc.new{|i,a| [i, a << File.size(i)]}
  F_EXT = Proc.new{|i,a| [i, a << File.extname(i)]}
  F_Trailer = Proc.new{|i,a| a}

  def criteria(opt)
    f = F_Bootstrap
    opt.each_byte do |c|
      case c
      when ?s
        f *= F_SIZE
      when ?e
        f *= F_EXT
      end
    end
    f * F_Trailer
  end

  puts Dir["*"].sort_by(&criteria("se"))


-- Gotoken