Add proper memo_wise initialization for inherited classes

CHANGELOG.md

@@ -7,7 +7,9 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased](https://github.com/panorama-ed/memo_wise/compare/v1.13.0...HEAD)
 
-**Gem enhancements:** none
+**Gem enhancements:**
+
+- Allow using `MemoWise` in subclasses of classes that have `prepend MemoWise` [[#392]](https://github.com/panorama-ed/memo_wise/pull/392)
 
 _No breaking changes!_
 

README.md

@@ -116,17 +116,17 @@ Benchmarks are run in GitHub Actions, and the tables below are updated with ever
 
 Results using Ruby 3.4.3:
 
-|Method arguments|`alt_memery` (2.1.0)|`dry-core`\* (1.1.0)|`memery` (1.7.0)|`memoist3` (1.0.0)|`short_circu_it` (0.29.3)|
+|Method arguments|`alt_memery` (2.1.0)|`dry-core` (1.1.0)|`memery` (1.7.0)|`memoist3` (1.0.0)|`short_circu_it` (0.29.3)|
 |--|--|--|--|--|--|
-|`()` (none)|12.20x|0.57x|3.31x|2.76x|18.45x|
-|`(a)`|9.75x|0.98x|3.76x|14.54x|13.96x|
-|`(a, b)`|7.59x|0.82x|2.92x|11.39x|10.87x|
-|`(a:)`|14.89x|0.97x|6.39x|19.76x|12.60x|
-|`(a:, b:)`|12.64x|0.86x|5.43x|21.05x|10.70x|
-|`(a, b:)`|12.25x|0.84x|5.22x|16.12x|10.31x|
-|`(a, *args)`|1.89x|0.65x|0.73x|2.84x|2.70x|
-|`(a:, **kwargs)`|2.86x|0.71x|1.21x|4.79x|2.42x|
-|`(a, *args, b:, **kwargs)`|1.81x|0.62x|0.83x|3.03x|1.52x|
+|`()` (none)|15.07x|0.65x|8.09x|6.68x|17.71x|
+|`(a)`|7.75x|1.00x|5.74x|15.19x|10.51x|
+|`(a, b)`|6.32x|0.87x|4.61x|12.51x|8.63x|
+|`(a:)`|10.89x|1.01x|6.83x|20.19x|9.97x|
+|`(a:, b:)`|8.99x|0.88x|5.63x|21.51x|8.29x|
+|`(a, b:)`|8.80x|0.87x|5.52x|16.51x|8.18x|
+|`(a, *args)`|2.14x|0.87x|1.41x|4.10x|2.73x|
+|`(a:, **kwargs)`|2.73x|0.75x|2.45x|7.68x|3.19x|
+|`(a, *args, b:, **kwargs)`|1.77x|0.73x|1.12x|4.38x|1.66x|
 
 \* `dry-core`
 [may cause incorrect behavior caused by hash collisions](https://github.com/dry-rb/dry-core/issues/63).

lib/memo_wise.rb

@@ -105,6 +105,13 @@ def allocate
         MemoWise::InternalAPI.create_memo_wise_state!(super)
       end
 
+      # [`Class#inherited`](https://ruby-doc.org/3.3.1/Class.html#method-i-inherited) is used here
+      # to make MemoWise methods available in subclasses.
+      def inherited(subclass)
+        super
+        subclass.prepend(MemoWise)
+      end
+
       # NOTE: See YARD docs for {.memo_wise} directly below this method!
       def memo_wise(method_name_or_hash)
         klass = self

spec/adding_methods_spec.rb

@@ -20,6 +20,7 @@
         memo_wise
         preset_memo_wise
         reset_memo_wise
+        inherited
       ].to_set
     end
 

spec/memo_wise_spec.rb

@@ -754,6 +754,14 @@ def module1_method
       end
     end
 
+    context "when a class inherits from a parent class where memo_wise is defined" do
+      include_context "with context for inherited class instance"
+
+      let(:target) { instance }
+
+      it_behaves_like "#memo_wise shared examples"
+    end
+
     context "with module mixed into other classes" do
       context "when extended" do
         context "when defined with 'def'" do

spec/spec_helper.rb

@@ -50,6 +50,7 @@
 require "support/shared_context_for_instance_methods"
 require "support/shared_context_for_class_methods_via_self_dot"
 require "support/shared_context_for_class_methods_via_class_scope"
+require "support/shared_context_for_inherited_class_instance"
 require "support/shared_context_for_module_methods_via_self_dot"
 require "support/shared_context_for_module_methods_via_class_scope"
 require "support/shared_context_for_module_methods_via_normal_scope"

spec/support/shared_context_for_inherited_class_instance.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+RSpec.shared_context "with context for inherited class instance" do
+  let(:parent_class) do
+    Class.new do
+      prepend MemoWise
+    end
+  end
+
+  let(:inherited_class_with_memo) do
+    Class.new(parent_class) do
+      def initialize; end
+
+      DefineMethodsForTestingMemoWise.define_methods_for_testing_memo_wise(
+        target: self,
+        via: :instance
+      )
+    end
+  end
+
+  let(:instance) { inherited_class_with_memo.new }
+end