Basic hooks and anchors in Ruby.

hooks.rb

class AbstractHook
  @oHook =  nil

  def sethook( *args )
    args.each { |arg| 
      if @hook.nil?
        @hook = arg
      else
        @hook.sethook( arg )
      end
    }
  end  

  def process( *args )
    if preprocess( args )
      execute( args )
    end

    if ! @hook.nil?
      @hook.process( args )
    end
    postprocess( args )

  end

  def preprocess( *args )
    # Override to implement whether this hook executes
    true
  end

  def postprocess( *args )

  end

  def execute( *args )
    # Implement the hook here
  end
end

class HookAnchor < AbstractHook
  attr_accessor :ahook

  def initialize( *args )
    self.ahook = [] # on object creation initialize this to an array
    args.each { |arg| 
      self.ahook << args
    }
  end

  def execute( *args )
    @ahook.each { | hook | 
      hook.process( args )
    }
  end
end


# ========================
# Sample implementation
# ========================
class TalkyHook < AbstractHook
  def execute( *args )
    puts self.class.name
  end
end

class Hook1 < TalkyHook 
  def initialize( *args )
    puts "-------"
    puts args.join( " " )
  end
end

class Hook2 < TalkyHook 
end

class Hook3 < TalkyHook 
end

x = Hook1.new( "Hooks assigned discretely" )
x.sethook( Hook2.new )
x.sethook( Hook3.new )
x.process


y = Hook1.new( "Hooks assigned in batch" )
y.sethook( Hook2.new , Hook3.new )
y.process


class TalkyAnchor < HookAnchor
  def initialize( *args )
    super args
    puts "-------"
    puts args.join( " " )
  end
end


z = TalkyAnchor.new( "An anchor with a couple of hook chains" )
z.ahook << x << y
z.process