Retain scope when rewriting block source with instance_eval

Rafa_F · August 4, 2013, 4:35am

success.rb works by using the block as is. self.instance_eval &block

gist.github.com

https://gist.github.com/bootstraponline/6148819

fail.rb

require 'rubygems'
require 'method_source'

ary = []

class Test
  def self.run &block
    define_method :run_method do
      # https://www.ruby-forum.com/topic/4416134#1117671
      eval %(ary << 1; puts 'complete'), block.binding

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success.rb

ary = []

class Test
  def self.run &block
    define_method :run_method do
      # ary is in scope
      self.instance_eval &block
    end

    Test.new.run_method

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I’m rewriting the block source code using ruby2ruby and then passing
that as a string to self.instance_eval. fail.rb contains the simple
failure case. The ary var is out of scope.

Is there a way to retain the
original scope of the block? I want to pass a string to instance_eval
and eval it within the scope of the block.

Thanks.

bootstrap_o · August 4, 2013, 2:24pm

instance_eval by definition evaluates within the scope of the
receiving instance. You don’t need that here. You could just use eval
with a binding:

eval %(ary << 1; puts 'complete'), block.binding

Regards,
Sean

bootstrap_o · August 4, 2013, 5:38pm

That works. Thank you!