closure tip

closure is so fun.
well design for meta programming.

note 1:

 01 #!/usr/bin/env ruby        
 02
 03 class Hash
 04     def find_all
 05         temp_hash = {}
 06         each {|key,value| temp_hash[key] = value if yield(key,value) }
 07         temp_hash
 08     end 
 09 end 
 10 
 11 square = { 0 => 0, 1 => 1, 2 => 4, 3 => 9 }
 12 
 13 new = square.find_all { |key,value| key > 1 }
 14 puts new.inspect

pass yield values.

note 2:

 01 #!/usr/bin/env ruby        
 02
 03 class Person
 04     attr_accessor :name
 05     def initialize(name)
 06         @name = name       
 07     end
 08 end
 09 
 10 def command(obj,method)    
 11     obj.each {|x| yield x.send(method)}
 12 end
 13 
 14 family = []
 15 
 16 %w(shelling sherry appollo).each do |name|
 17     family.push Person.new(name)    
 18 end
 19 
 20 command family, :name do |x|
 21     puts "hello, I am #{x}."
 22 end

Every object in array call the same function.