gistfile1.txt

[~/programming/sinatra]$ irb
ruby-1.8.7-p330 :001 > class Array; def save_map(&blk); self.instance_variable_set(:@map_blk, blk) end; def call_saved_map; self.map(&self.instance_variable_get(:@map_blk)) end end
 => nil 
ruby-1.8.7-p330 :002 > a = [1,2,3]
 => [1, 2, 3] 
ruby-1.8.7-p330 :003 > a.save_map {|i| i * 2 }
 => #<Proc:0x00000001003463a8@(irb):3> 
ruby-1.8.7-p330 :004 > a
 => [1, 2, 3] 
ruby-1.8.7-p330 :005 > a.call_saved_map
 => [2, 4, 6] 
ruby-1.8.7-p330 :006 >