Implement a draft version of ActiveMethod

Author: hoppergee

lib/active_method.rb

@@ -3,6 +3,5 @@
 require_relative "active_method/version"
 
 module ActiveMethod
-  class Error < StandardError; end
-  # Your code goes here...
+  autoload :Base, "active_method/base"
 end

lib/active_method/base.rb

@@ -0,0 +1,110 @@
+module ActiveMethod
+  class Base
+
+    class Argument
+      attr_reader :name, :default
+
+      def initialize(name, default: nil)
+        @name = name
+        @default = default
+      end
+    end
+
+    class << self
+
+      def call(*args)
+        new(*args).call
+      end
+
+      def arguments
+        class_variable_get(:@@arguments)
+      end
+
+      def keyword_arguments
+        class_variable_get(:@@keyword_arguments)
+      end
+
+      private
+
+      def method_missing(method_name, *args)
+        case method_name.to_s
+        when /^argument(_\d)*$/
+          init_arguments
+          parse_argument(method_name, *args)
+        when 'keyword_argument'
+          init_keyword_arguments
+          parse_keyword_argument(*args)
+        else
+          super
+        end
+      end
+
+      def parse_argument(method_name, name, opts = {})
+        _, index = method_name.to_s.split('_')
+        if index.nil?
+          index = (arguments.keys.max || 0) + 1
+        end
+        arguments[Integer(index)] = Argument.new(name, **opts)
+
+        define_method name do
+          instance_variable_get("@#{name}")
+        end
+      end
+
+      def parse_keyword_argument(name, opts = {})
+        keyword_arguments << Argument.new(name, **opts)
+
+        define_method name do
+          instance_variable_get("@#{name}")
+        end
+      end
+
+      def init_arguments
+        return if self.class_variable_defined?(:@@arguments)
+
+        self.class_variable_set(:@@arguments, {})
+      end
+
+      def init_keyword_arguments
+        return if self.class_variable_defined?(:@@keyword_arguments)
+
+        self.class_variable_set(:@@keyword_arguments, [])
+      end
+    end
+
+    def initialize(*args)
+      arguments.each do |index, argument|
+        begin
+          instance_variable_set("@#{argument.name}", args.fetch(index - 1))
+        rescue IndexError
+          instance_variable_set("@#{argument.name}", argument.default)
+        end
+      end
+
+      opts = args[arguments.count] || {}
+      keyword_arguments.each do |argument|
+        if opts.key?(argument.name.to_sym)
+          instance_variable_set("@#{argument.name}", opts[argument.name.to_sym])
+        elsif opts.key?(argument.name.to_s)
+          instance_variable_set("@#{argument.name}", opts[argument.name.to_s])
+        else
+          instance_variable_set("@#{argument.name}", argument.default)
+        end
+      end
+    end
+
+    def call
+    end
+
+    private
+
+    def arguments
+      self.class.arguments
+    end
+
+    def keyword_arguments
+      self.class.keyword_arguments
+    end
+
+  end
+end