lib/sinclair/method_definition.rb in sinclair-1.1.3 vs lib/sinclair/method_definition.rb in sinclair-1.2.0

@@ -4,34 +4,86 @@
   # @api private
   # @author darthjee
   #
   # Definition of the code or block to be aded as method
   class MethodDefinition
+    include Sinclair::OptionsParser
+    # Default options of initialization
+    DEFAULT_OPTIONS = {
+      cached: false
+    }.freeze
+
     # Returns a new instance of MethodDefinition
     #
     # @overload initialize(name, code)
+    #   @example
+    #     Sinclair::MethodDefinition.new(:name, '@name')
+    #
     # @overload initialize(name, &block)
+    #   @example
+    #     Sinclair::MethodDefinition.new(:name) { @name }
     #
-    # @param name  [String,Symbol] name of the method
-    # @param code  [String] code to be evaluated as method
-    # @param block [Proc] block with code to be added as method
-    #
-    # @example
-    #   Sinclair::Method.new(:name, '@name')
-    #
-    # @example
-    #   Sinclair::Method.new(:name) { @name }
-    def initialize(name, code = nil, &block)
-      @name = name
-      @code = code
-      @block = block
+    # @param name    [String,Symbol] name of the method
+    # @param code    [String] code to be evaluated as method
+    # @param block   [Proc] block with code to be added as method
+    # @param options [Hash] Options of construction
+    # @option options cached [Boolean] Flag telling to create
+    #   a method with cache
+    def initialize(name, code = nil, **options, &block)
+      @name =    name
+      @code =    code
+      @options = DEFAULT_OPTIONS.merge(options)
+      @block =   block
     end
 
     # Adds the method to given klass
     #
     # @param klass [Class] class which will receive the new method
     #
+    # @example Using string method with no options
+    #   class MyModel
+    #   end
+    #
+    #   instance = MyModel.new
+    #
+    #   method_definition = Sinclair::MethodDefinition.new(
+    #     :sequence, '@x = @x.to_i ** 2 + 1'
+    #   )
+    #
+    #   method_definition.build(klass)  # adds instance_method :sequence to
+    #                                  # MyModel instances
+    #
+    #   instance.instance_variable_get(:@x)        # returns nil
+    #
+    #   instance.sequence               # returns 1
+    #   instance.sequence               # returns 2
+    #   instance.sequence               # returns 5
+    #
+    #   instance.instance_variable_get(:@x)        # returns 5
+    #
+    # @example Using string method with no options
+    #   class MyModel
+    #   end
+    #
+    #   instance = MyModel.new
+    #
+    #   method_definition = Sinclair::MethodDefinition.new(:sequence) do
+    #     @x = @x.to_i ** 2 + 1
+    #   end
+    #
+    #   method_definition.build(klass)  # adds instance_method :sequence to
+    #                                  # MyModel instances
+    #
+    #   instance.instance_variable_get(:@sequence) # returns nil
+    #   instance.instance_variable_get(:@x)        # returns nil
+    #
+    #   instance.sequence               # returns 1
+    #   instance.sequence               # returns 1 (cached value)
+    #
+    #   instance.instance_variable_get(:@sequence) # returns 1
+    #   instance.instance_variable_get(:@x)        # returns 1
+    #
     # @return [Symbol] name of the created method
     def build(klass)
       if code.is_a?(String)
         build_code_method(klass)
       else
@@ -41,22 +93,50 @@
 
     private
 
     # @private
     attr_reader :name, :code, :block
+    delegate :cached, to: :options_object
 
     # @private
     #
+    # Flag telling to use cached method
+    #
+    # @return [Boolean]
+    alias cached? cached
+
+    # @private
+    #
     # Add method from block
     #
     # @return [Symbol] name of the created method
     def build_block_method(klass)
-      klass.send(:define_method, name, block)
+      klass.send(:define_method, name, method_block)
     end
 
     # @private
     #
+    # Returns the block that will be used for method creattion
+    #
+    # @return [Proc]
+    def method_block
+      return block unless cached?
+
+      inner_block = block
+      method_name = name
+
+      proc do
+        instance_variable_get("@#{method_name}") ||
+          instance_variable_set(
+            "@#{method_name}",
+            instance_eval(&inner_block)
+          )
+      end
+    end
+
+    # @private
+    #
     # Add method from String code
     #
     # @return [Symbol] name of the created method
     def build_code_method(klass)
       klass.module_eval(code_definition, __FILE__, __LINE__ + 1)
@@ -66,12 +146,13 @@
     #
     # Builds full code of method
     #
     # @return [String]
     def code_definition
+      code_line = cached? ? "@#{name} ||= #{code}" : code
       <<-CODE
       def #{name}
-        #{code}
+        #{code_line}
       end
       CODE
     end
   end
 end