using method missing to reduce the code in ruby

Question

I have a set of Class methods which is :

class << self
def increment_value
 self.first.increment_value
end
def max_work_hours_per_day
 self.first.max_work_hours_per_day
end
def fast_completion_day
 self.first.fast_completion_day
end
def super_fast_completion_day
 self.first.super_fast_completion_day
end
def ludicrous_completion_day
 self.first.ludicrous_completion_day
end
def budget_completion_day
 self.first.budget_completion_day
end
end

Since all the methods call self.first.atttibute where attribute is the same name as function name. I think we can reduce this to a single method. Something like method_missing is there in Ruby , but since I am not very good at meta programming , I am seeking advise here.

• hobbs: This and this look like reasonabl nice ways to handle delegation in Ruby.

Answer 1

Ruby already has a module which allows you to forward specific methods to a given object in its standard library: the Forwardable module.

Using it you can write code like this:

class << self
 extend Forwardable
 def_delegators :first, :increment_value, :max_work_hours_per_day #...
end

I think spelling out the methods you want to forward like this is preferable to simply forwarding everything as it won't accidentally forward something you don't want to forward. It also does not affect the error message when calling a method that does not exist.