follower.rb in policy-2.0.0

- old
+ new
@@ -1,142 +1,102 @@
 # encoding: utf-8
 
 module Policy
 
-  # Adds features for the object to follow external policies
+  # Interface for the class that follows policies
   module Follower
 
-    require_relative "follower/names"
-    require_relative "follower/followed_policy"
-    require_relative "follower/followed_policies"
-
-    # Methods to be added to the class the module is included to
-    #
-    # @private
+    # Methods to be added to the follower class
     module ClassMethods
 
-      # @!attribute [r] followed_policies
-      # The collection of policies to be followed by instances of the class
+      # Declares a policy to be followed
       #
-      # @return [Policy::Follower::FollowedPolicies]
+      # Mutates the object by adding an item to its {#policies}.
       #
-      # @private
-      def followed_policies
-        @followed_policies ||= FollowedPolicies.new
+      # @param [Symbol] name
+      #
+      # @return [:follows_policy] the name of the method
+      def follows_policy(name)
+        policies.add name
+
+        :follows_policy
       end
 
-      # Adds a policy to the list of {#followed_policies}
+      # Declares policies to be followed
       #
-      # @param [Class] policy
-      #   the policy object klass
-      # @param [Array<#to_sym>] attributes
-      #   the list of attributes of the instance the policy should be applied to
+      # Mutates the object by adding items to its {#policies}.
       #
-      # @option [#to_sym] :as
-      #   the name for the policy to be used for selecting it
-      #   in {#follow_policies!} and {#follow_policies?} methods
+      # @param [Symbol, Array<Symbol>] names
       #
-      # @return [undefined]
-      def follow_policy(policy, *attributes, as: nil)
-        object = FollowedPolicy.new(__policies__, policy, as, *attributes)
-        followed_policies.add object
+      # @return [:follows_policies] the name of the method
+      def follows_policies(*names)
+        names.each(&method(:follows_policy))
+
+        :follows_policies
       end
 
-      # Changes the namespace for applied policies
+      # @!attribute [r] policies
+      # The collection of followed policies
       #
-      # @example For Policies::Finances::TransferConsistency
-      #   use_policies Policies::Finances do
-      #     apply_policy :TransferConstistency, :debet, :credit
-      #   end
-      #
-      # @param [Module] namespace
-      #
-      # @yield the block in the current scope
-      #
-      # @return [undefined]
-      def use_policies(namespace, &block)
-        @__policies__ = namespace
-        instance_eval(&block)
-      ensure
-        @__policies__ = nil
+      # @return [Policy::Follower::Policies]
+      def policies
+        @policies ||= Policies.new(self)
       end
 
-      private
-
-      def __policies__
-        @__policies__ ||= self
-      end
-
     end
 
-    # Checks whether an instance meets selected policies
+    # Checks whether an object follows all its policies or subset of policies
     #
-    # Mutates the object by adding new #errors
+    # @overload follow_policies?()
+    #   Checks whether an object follows all registered policies
     #
-    # @param [Array<#to_sym>] names
-    #   the ordered list of names to select policies by
-    #   when not names selected all policies will be applied
+    # @overload follow_policies?(names)
+    #   Checks whether an object follows given policies
     #
-    # @raise [Policy::ViolationError]
-    #   unless all selected policies has been met
+    #   @param [#to_sym, Array<#to_sym>] names
     #
-    # @return [undefined]
-    def follow_policies!(*names)
-      followed_policies.apply_to self, *names
-    rescue ViolationError => error
-      collect_errors_from(error)
-      raise
-    end
-
-    # Syntax shugar for the {#follow_policies!} with one argument
+    #   @raise [Policy::Follower::NameError]
+    #     if the policy is not registered by name
     #
-    # @param [#to_sym] name
-    #   the name of the policy to follow
+    # @raise [NoMethodError]
+    #   if the name not implemented as follower's instance method
+    # @raise [ViolationError]
+    #   if the policy is violated by the follower
     #
-    # @raise (see #follow_policies!)
-    #
-    # @return [undefined]
-    def follow_policy!(name)
-      follow_policies! name
-    end
-
-    # Safely checks whether an instance meets selected policies
-    #
-    # Mutates the object by adding new #errors
-    #
-    # @param (see #follow_policies!)
-    #
-    # @return [Boolean]
+    # @return [true] if no exception being raised
     def follow_policies?(*names)
-      follow_policies!(*names)
+      __policies__
+        .subset(names)                       # raises NameError
+        .map(&method(:__send__))             # raises NoMethodError
+        .each(&method(:__validate_policy__)) # raises ViolationError
       true
-    rescue ViolationError
-      false
     end
 
-    # Syntax shugar for the {#follow_policies?} with one argument
+    # Checks whether an object follows given policy
     #
-    # @param  (see #follow_policy!)
+    # @param [#to_sym] name
+    #   the name of the policy to follow
     #
+    # @raise  (see #follow_policies?)
+    #
     # @return (see #follow_policies?)
     def follow_policy?(name)
       follow_policies? name
     end
 
-    private
-
-    # @!parse extend  Policy::Follower::ClassMethods
-    # @!parse include ActiveModel::Validations
+    # @private
     def self.included(klass)
-      klass.extend(ClassMethods).__send__(:include, Validations)
+      klass.instance_eval { extend ClassMethods }
     end
 
-    def followed_policies
-      @followed_policies ||= self.class.followed_policies
+    private
+
+    def __validate_policy__(policy)
+      fail ViolationError.new(self, policy) unless policy.valid?
     end
 
-    def collect_errors_from(exception)
-      exception.messages.each { |text| errors.add :base, text }
+    def __policies__
+      self.class.policies
     end
 
   end # module Follower
 
 end # module Policy