gistfile1.rb

class Object
  def with(obj, &block)
    obj.instance_eval &block
  end
end

h = { :a => 1, :b => 2 }
a = ["a", "b"]

with h do
  puts keys
  puts values
  #...
  puts a.size
end

#=> b\na\n2\n1\n2

@person = Person.new

with @person do
  self.firstname = "Florian"
  self.lastname = "Dutey"
  self.email = "fdutey@example.com"
  self.url = "http://blog.fdutey.com"
end

#self est obligatoire car sinon ruby considère que c'est une variable locale, comme au sein de l'objet.

@person.lastname #=> "Dutey"