Question

I am a ruby newb and am having a problem with procs created inside loops accessing loop variables. Here is a code file demonstrating the problem.

class Route     def initialize options = {}     options.each do |k,v|              self.instance_variable_set('@#{k}', v)             self.class.send(:define_method, k, proc{self.instance_variable_get('@#{k}')})       self.class.send(:define_method, '#{k}=', proc{|v| self.instance_variable_set('@#{k}', v)})         end     end end  routes = [] routes << Route.new({ :url=>'/one', :content=>'html1' }) routes << Route.new({ :url=>'/two', :content=>'html2' })  blocks = [] for route in routes         blocks << Proc.new { route.content } end  puts blocks[0].call #=> 'html2' puts blocks[1].call #=> 'html2' 

How can I make blocks[0].call return ‘html1’ and blocks[1].call return ‘html2’

Answer 1

You can create the Procs inside a block to provide each Proc a diferent context:

class Route   def initialize(options = {})     options.each do |k,v|        self.instance_variable_set('@#{k}', v)       self.class.send(:define_method, k, proc{self.instance_variable_get('@#{k}')})       self.class.send(:define_method, '#{k}=', proc{|v| self.instance_variable_set('@#{k}', v)})     end   end end  routes = [] routes << Route.new({ :url=>'/one', :content=>'html1' }) routes << Route.new({ :url=>'/two', :content=>'html2' })  blocks = routes.map { |e| Proc.new { e.content } }  puts blocks[0].call #=> 'html1' puts blocks[1].call #=> 'html2'