Validates that public instance methods of a class are defined.

instance_validator.rb

# Shows a crude way to enforce that a class implements
# required methods.  Use it like this:
#
# class OkClass
#   def foo; end
#   def bar; end
#   def baz; end
# end
#
#
# class NotOkClass
#   def foo; end
# end
#
#
# verifier = InstanceMethodVerifier.new([:foo, :bar, :baz])
# verifier.verify('OkClass')
# verifier.verify('NotOkClass')
#
# $ ruby instance_method_verifier.rb                                                                                                                                       14.Jun.11 15.21
# instance_method_verifier.rb:22:in `verify': Class NotOkClass is missing the following required functions: bar, baz (RuntimeError)
#	from instance_method_verifier.rb:42

class InstanceMethodValidator

  attr_accessor :required_function_names


  def initialize(required_function_names)
    @required_function_names = required_function_names
  end


  # klass can be either a class name or a class object.
  def validate(klass)

    if klass.is_a? String
      klass = Kernel.const_get(klass)
    end

    missing_function_names = required_function_names - klass.public_instance_methods

    unless missing_function_names.empty?
      raise Error.new("Class #{klass} is missing the following required functions: #{missing_function_names.join(", ")}.")
    end
  end


  class Error < RuntimeError
  end
end