From 8ed08c8c94339afa5b8bec8b4010dfb56efa7c98 Mon Sep 17 00:00:00 2001
From: Jose Solas Moreno <jsolas@buk.cl>
Date: Fri, 18 Jul 2025 19:04:59 -0400
Subject: [PATCH] Add after_compile hook

---
 docs/CHANGELOG.md              |  6 ++++
 lib/view_component/base.rb     | 12 ++++++++
 lib/view_component/compiler.rb |  7 +++++
 test/sandbox/test/base_test.rb | 55 ++++++++++++++++++++++++++++++++++
 4 files changed, 80 insertions(+)

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index e6bb654e2..e55dc6d6b 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -10,6 +10,12 @@ nav_order: 6
 
 ## main
 
+## 4.0.3
+
+* Add `after_compile` hook to enable extensions to run logic after component compilation. Extensions can override this instance method to add custom post-compilation behavior.
+
+    *Jose Solás*
+
 ## 4.0.2
 
 * Share the view context in tests to prevent out-of-order rendering issues for certain advanced use-cases, eg. testing instances of Rails' `FormBuilder`.
diff --git a/lib/view_component/base.rb b/lib/view_component/base.rb
index 97ba41815..28668fcd2 100644
--- a/lib/view_component/base.rb
+++ b/lib/view_component/base.rb
@@ -611,6 +611,18 @@ def __vc_compiled?
         __vc_compiler.compiled?
       end
 
+      # Called after a component class has been compiled.
+      #
+      # Extensions can override this instance method to run logic after
+      # compilation (e.g., generate helpers, register metadata, etc.).
+      #
+      # By default, this is a no-op. The compiler will invoke this method on an
+      # uninitialized instance using `allocate` to avoid requiring initializer
+      # arguments.
+      def after_compile
+        # no-op by default
+      end
+
       # @private
       def __vc_ensure_compiled
         __vc_compile unless __vc_compiled?
diff --git a/lib/view_component/compiler.rb b/lib/view_component/compiler.rb
index 130ecbde3..613290c66 100644
--- a/lib/view_component/compiler.rb
+++ b/lib/view_component/compiler.rb
@@ -52,6 +52,13 @@ def compile(raise_errors: false, force: false)
         @component.__vc_build_i18n_backend
 
         CompileCache.register(@component)
+
+        # Invoke instance-level after_compile hook without calling initialize.
+        begin
+          @component.allocate.after_compile
+        rescue NoMethodError
+          # no-op
+        end
       end
     end
 
diff --git a/test/sandbox/test/base_test.rb b/test/sandbox/test/base_test.rb
index a9c0e2552..2d5aad28f 100644
--- a/test/sandbox/test/base_test.rb
+++ b/test/sandbox/test/base_test.rb
@@ -195,4 +195,59 @@ def test_uses_module_configuration
     assert_equal false, TestAlreadyConfigurableModule::SomeComponent.instrumentation_enabled
     assert_equal false, TestAlreadyConfiguredModule::SomeComponent.instrumentation_enabled
   end
+
+  def test_after_compile_hook_called_on_compile
+    klass = Class.new(ViewComponent::Base) do
+      @@calls = 0
+
+      def self.calls
+        @@calls
+      end
+
+      def after_compile
+        @@calls += 1
+      end
+
+      erb_template ""
+    end
+
+    self.class.const_set(:TempHookComponent, klass)
+    ViewComponent::CompileCache.invalidate_class!(klass)
+
+    ViewComponent::Compiler.new(klass).compile(force: true)
+    assert_equal 1, klass.calls
+  ensure
+    self.class.send(:remove_const, :TempHookComponent) if self.class.const_defined?(:TempHookComponent)
+    ViewComponent::CompileCache.invalidate_class!(klass) if defined?(klass)
+  end
+
+  def test_after_compile_not_called_on_cached_compile
+    klass = Class.new(ViewComponent::Base) do
+      @@calls = 0
+
+      def self.calls
+        @@calls
+      end
+
+      def after_compile
+        @@calls += 1
+      end
+
+      erb_template ""
+    end
+
+    self.class.const_set(:TempHookCachedComponent, klass)
+    ViewComponent::CompileCache.invalidate_class!(klass)
+
+    compiler = ViewComponent::Compiler.new(klass)
+    compiler.compile(force: true)
+    assert_equal 1, klass.calls
+
+    # compile again without force -> should not call hook again
+    compiler.compile
+    assert_equal 1, klass.calls
+  ensure
+    self.class.send(:remove_const, :TempHookCachedComponent) if self.class.const_defined?(:TempHookCachedComponent)
+    ViewComponent::CompileCache.invalidate_class!(klass) if defined?(klass)
+  end
 end