Question

I have the following problem:

I am renaming all instance methods for a specific class, using alias_method_chain in order to give them extra behavior. I get all instance methods with the following line of code:

self.class.instance_methods(false)

By doing that I get all my instance methods, but I also get the gettes and setters that I defined using attr_accessor / attr_reader / attr_writer.
What I need to do, is detect which methods returned from the previous line of code are accessor methods because I don’t want to rename those.

Obviusly, I can detect if the method name has a “=” at the end, that would make it a setter, and if that exists, I can see if the getter is defined aswell, but what happens when there is only a getter defined? How can I check that? Specially considering that the attributes are not available for the class method “instance_variables” until they’re initialized?

Thanks for the help!

Answer 1

You may extend attr_reader… to store the methods.

class Object
  class << self
    attr_reader :accessors
    attr_reader :setters
    attr_reader :getters

    alias :attr_accessor_old :attr_accessor
    def attr_accessor(methname)
      (@accessors ||= [] ) << methname
      attr_accessor_old methname
    end

    alias :attr_writer_old :attr_writer
    def attr_writer(methname)
      (@setters ||= [] ) << "#{methname}=".to_sym
      attr_writer_old methname
    end

    alias :attr_reader_old :attr_reader
    def attr_reader(methname)
      (@getters ||= [] ) << methname
      attr_reader_old methname
    end

  end
end

class Test
  attr_accessor :acc
  attr_reader :read
  attr_writer :write
end
Test.instance_methods(false).each{|meth|
  puts "#{meth} is an accessor" if Test.accessors.include?(meth)
  puts "#{meth} is a setter" if Test.setters.include?(meth)
  puts "#{meth} is a getter" if Test.getters.include?(meth)
}

Result:

acc is an accessor
read is a getter
write= is a setter