Define a class method in a module with a variable name - ruby

Question

I created a module which is included in a class. In the module, I am trying to define a method that is the downcased version of a class name without Filter. So ShowFilter would have a method called show that returns the class Show. I get "NoMethodError:
undefined method `show' for ShowFilter:Class"
module Filters
module Base
module ClassMethods
##filters = {}
def filter name, &block
##filters[name] = block
end
def run query = {}
query.each do |name, value|
##filters[name.to_sym].call(value) unless ##filters[name.to_sym].nil?
end
self
end
def self.extended(base)
name = base.class.name.gsub(/filter/i, '')
define_method(name.downcase.to_sym) { Kernel.const_get name }
end
end
def self.included base
base.extend ClassMethods
end
end
end
class ShowFilter
include Filters::Base
filter :name do |name|
self.show.where(:name => name)
end
end
EDIT: Example of use
class ShowController < ApplicationController
def index
ShowFilter.run params[:query]
end
end

Answer 1

When you define Filters::Base::ClassMethods, it evaluates self in that context so the method you'll end up defining is ClassMethods.classmethods (since the gsub won't do anything).
Like the included hook you tapped into in Base, you want to use extended in ClassMethods:
module Filters
module Base
module ClassMethods
##filters = {}
def filter name, &block
##filters[name] = block
end
def run query = {}
query.each do |name, value|
##filters[name.to_sym].call(value) unless ##filters[name.to_sym].nil?
end
Object.const_get(self.to_s.gsub('Filter', ''))
end
def self.extended(base)
define_method(base.to_s.downcase.gsub('filter', '').to_sym) do
Object.const_get(self.to_s.gsub('Filter', ''))
end
end
end
def self.included base
base.extend ClassMethods
end
end
end
class ShowFilter
include Filters::Base
filter :title do |title|
self.show.where(:title => title)
end
end