Support allocated instances

lib/memo_wise.rb

@@ -23,14 +23,14 @@
 #   - {file:README.md} for general project information.
 #
 module MemoWise # rubocop:disable Metrics/ModuleLength
-  # Constructor to setup memoization state before
+  # Constructor to set up memoization state before
   # [calling the original](https://medium.com/@jeremy_96642/ruby-method-auditing-using-module-prepend-4f4e69aacd95)
   # constructor.
   #
   # - **Q:** Why is [Module#prepend](https://ruby-doc.org/core-2.7.2/Module.html#method-i-prepend)
   #          important here
   #          ([more info](https://medium.com/@leo_hetsch/ruby-modules-include-vs-prepend-vs-extend-f09837a5b073))?
-  # - **A:** To setup *mutable state* inside the instance, even if the original
+  # - **A:** To set up *mutable state* inside the instance, even if the original
   #          constructor will then call
   #          [Object#freeze](https://ruby-doc.org/core-2.7.2/Object.html#method-i-freeze).
   #
@@ -211,13 +211,16 @@ def self.original_class_from_singleton(klass)
   # @param [Object] obj
   #   Object in which to create mutable state to store future memoized values
   #
+  # @return [Object] the passed-in obj
   def self.create_memo_wise_state!(obj)
     unless obj.instance_variables.include?(:@_memo_wise)
       obj.instance_variable_set(
         :@_memo_wise,
         Hash.new { |h, k| h[k] = {} }
       )
     end
+
+    obj
   end
 
   # @private
@@ -236,6 +239,23 @@ def self.create_memo_wise_state!(obj)
   #
   def self.prepended(target) # rubocop:disable Metrics/PerceivedComplexity
     class << target
+      # Allocator to set up memoization state before
+      # [calling the original](https://medium.com/@jeremy_96642/ruby-method-auditing-using-module-prepend-4f4e69aacd95)
+      # allocator.
+      #
+      # This is necessary in addition to the `#initialize` method definition
+      # above because
+      # [`Class#allocate`](https://ruby-doc.org/core-3.0.0/Class.html#method-i-allocate)
+      # bypasses `#initialize`, and when it's used (e.g.,
+      # [in ActiveRecord](https://github.com/rails/rails/blob/a395c3a6af1e079740e7a28994d77c8baadd2a9d/activerecord/lib/active_record/persistence.rb#L411))
+      # we still need to be able to access MemoWise's instance variable. Despite
+      # Ruby documentation indicating otherwise, `Class#new` does not call
+      # `Class#allocate`, so we need to override both.
+      #
+      def allocate
+        MemoWise.create_memo_wise_state!(super)
+      end
+
       # NOTE: See YARD docs for {.memo_wise} directly below this method!
       def memo_wise(method_name_or_hash) # rubocop:disable Metrics/PerceivedComplexity
         klass = self

spec/memo_wise_spec.rb

@@ -7,72 +7,101 @@
     Class.new do
       prepend MemoWise
 
-      def initialize
-        @no_args_counter = 0
-        @with_positional_args_counter = 0
-        @with_positional_and_splat_args_counter = 0
-        @with_keyword_args_counter = 0
-        @with_keyword_and_double_splat_args_counter = 0
-        @with_positional_and_keyword_args_counter = 0
-        @with_positional_splat_keyword_and_double_splat_args_counter = 0
-        @special_chars_counter = 0
-        @false_method_counter = 0
-        @true_method_counter = 0
-        @nil_method_counter = 0
-        @private_memowise_method_counter = 0
-        @protected_memowise_method_counter = 0
-        @public_memowise_method_counter = 0
-        @proc_method_counter = 0
-      end
-
-      attr_reader :no_args_counter,
-                  :with_positional_args_counter,
-                  :with_positional_and_splat_args_counter,
-                  :with_keyword_args_counter,
-                  :with_keyword_and_double_splat_args_counter,
-                  :with_positional_and_keyword_args_counter,
-                  :with_positional_splat_keyword_and_double_splat_args_counter,
-                  :special_chars_counter,
-                  :false_method_counter,
-                  :true_method_counter,
-                  :nil_method_counter,
-                  :private_memowise_method_counter,
-                  :protected_memowise_method_counter,
-                  :public_memowise_method_counter,
-                  :proc_method_counter
+      def no_args_counter
+        @no_args_counter || 0
+      end
+
+      def with_positional_args_counter
+        @with_positional_args_counter || 0
+      end
+
+      def with_positional_and_splat_args_counter
+        @with_positional_and_splat_args_counter || 0
+      end
+
+      def with_keyword_args_counter
+        @with_keyword_args_counter || 0
+      end
+
+      def with_keyword_and_double_splat_args_counter
+        @with_keyword_and_double_splat_args_counter || 0
+      end
+
+      def with_positional_and_keyword_args_counter
+        @with_positional_and_keyword_args_counter || 0
+      end
+
+      def with_positional_splat_keyword_and_double_splat_args_counter
+        @with_positional_splat_keyword_and_double_splat_args_counter || 0
+      end
+
+      def special_chars_counter
+        @special_chars_counter || 0
+      end
+
+      def false_method_counter
+        @false_method_counter || 0
+      end
+
+      def true_method_counter
+        @true_method_counter || 0
+      end
+
+      def nil_method_counter
+        @nil_method_counter || 0
+      end
+
+      def private_memowise_method_counter
+        @private_memowise_method_counter || 0
+      end
+
+      def protected_memowise_method_counter
+        @protected_memowise_method_counter || 0
+      end
+
+      def public_memowise_method_counter
+        @public_memowise_method_counter || 0
+      end
+
+      def proc_method_counter
+        @proc_method_counter || 0
+      end
 
       def no_args
-        @no_args_counter += 1
+        @no_args_counter = no_args_counter + 1
         "no_args"
       end
       memo_wise :no_args
 
       def with_positional_args(a, b) # rubocop:disable Naming/MethodParameterName
-        @with_positional_args_counter += 1
+        @with_positional_args_counter = with_positional_args_counter + 1
         "with_positional_args: a=#{a}, b=#{b}"
       end
       memo_wise :with_positional_args
 
       def with_positional_and_splat_args(a, *args) # rubocop:disable Naming/MethodParameterName
-        @with_positional_and_splat_args_counter += 1
+        @with_positional_and_splat_args_counter =
+          with_positional_and_splat_args_counter + 1
         "with_positional_and_splat_args: a=#{a}, args=#{args}"
       end
       memo_wise :with_positional_and_splat_args
 
       def with_keyword_args(a:, b:) # rubocop:disable Naming/MethodParameterName
-        @with_keyword_args_counter += 1
+        @with_keyword_args_counter = with_keyword_args_counter + 1
         "with_keyword_args: a=#{a}, b=#{b}"
       end
       memo_wise :with_keyword_args
 
       def with_keyword_and_double_splat_args(a:, **kwargs) # rubocop:disable Naming/MethodParameterName
-        @with_keyword_and_double_splat_args_counter += 1
+        @with_keyword_and_double_splat_args_counter =
+          with_keyword_and_double_splat_args_counter + 1
         "with_keyword_and_double_splat_args: a=#{a}, kwargs=#{kwargs}"
       end
       memo_wise :with_keyword_and_double_splat_args
 
       def with_positional_and_keyword_args(a, b:) # rubocop:disable Naming/MethodParameterName
-        @with_positional_and_keyword_args_counter += 1
+        @with_positional_and_keyword_args_counter =
+          with_positional_and_keyword_args_counter + 1
         "with_positional_and_keyword_args: a=#{a}, b=#{b}"
       end
       memo_wise :with_positional_and_keyword_args
@@ -83,52 +112,54 @@ def with_positional_splat_keyword_and_double_splat_args(
         b:, # rubocop:disable Naming/MethodParameterName
         **kwargs
       )
-        @with_positional_splat_keyword_and_double_splat_args_counter += 1
+        @with_positional_splat_keyword_and_double_splat_args_counter =
+          with_positional_splat_keyword_and_double_splat_args_counter + 1
         "with_positional_splat_keyword_and_double_splat_args: "\
           "a=#{a}, args=#{args} b=#{b} kwargs=#{kwargs}"
       end
       memo_wise :with_positional_splat_keyword_and_double_splat_args
 
       def special_chars?
-        @special_chars_counter += 1
+        @special_chars_counter = special_chars_counter + 1
         "special_chars?"
       end
       memo_wise :special_chars?
 
       def false_method
-        @false_method_counter += 1
+        @false_method_counter = false_method_counter + 1
         false
       end
       memo_wise :false_method
 
       def true_method
-        @true_method_counter += 1
+        @true_method_counter = true_method_counter + 1
         true
       end
       memo_wise :true_method
 
       def nil_method
-        @nil_method_counter += 1
+        @nil_method_counter = nil_method_counter + 1
         nil
       end
       memo_wise :nil_method
 
       def private_memowise_method
-        @private_memowise_method_counter += 1
+        @private_memowise_method_counter = private_memowise_method_counter + 1
         "private_memowise_method"
       end
       private :private_memowise_method
       memo_wise :private_memowise_method
 
       def protected_memowise_method
-        @protected_memowise_method_counter += 1
+        @protected_memowise_method_counter =
+          protected_memowise_method_counter + 1
         "protected_memowise_method"
       end
       protected :protected_memowise_method
       memo_wise :protected_memowise_method
 
       def public_memowise_method
-        @public_memowise_method_counter += 1
+        @public_memowise_method_counter = public_memowise_method_counter + 1
         "public_memowise_method"
       end
       memo_wise :public_memowise_method
@@ -137,7 +168,7 @@ def public_memowise_method
       def unmemoized_method; end
 
       def proc_method(proc)
-        @proc_method_counter += 1
+        @proc_method_counter = proc_method_counter + 1
         proc.call
       end
       memo_wise :proc_method
@@ -304,6 +335,15 @@ def self.with_positional_args(a, b) # rubocop:disable Naming/MethodParameterName
       end
     end
 
+    context "when instances are created with Class#allocate" do
+      let(:instance) { class_with_memo.allocate }
+
+      it "memoizes correctly" do
+        expect(Array.new(4) { instance.no_args }).to all eq("no_args")
+        expect(instance.no_args_counter).to eq(1)
+      end
+    end
+
     context "with class methods" do
       context "when defined with 'def self.'" do
         let(:class_with_memo) do