deprecate.rb

class Module
  def deprecate(*methodNames)
    methodNames.each do |methodName|
      module_eval <<END
      alias_method :deprecated_#{methodName}, :#{methodName}
	def #{methodName}(*args, &block)
	  $stderr.puts "Warning: calling deprecated method #{self}.#{methodName}"
	  return deprecated_#{methodName}(*args, &block)
	end
END
      end
  end
end

class Foo
  def print; puts "foo"; end
end

Foo.new.print

class Foo
  deprecate :print
end

Foo.new.print