From b9d96dc9094b90d1486a044d2822a9df9621d78a Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 16 Apr 2025 00:50:57 +0300
Subject: [PATCH] Allow overriding the base class of BufferedComponent

It still has to ultimately derive from Component, but this allows
inserting an intermediate base class.
---
 source/game/component.h | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/source/game/component.h b/source/game/component.h
index 6127cd4..9b78f96 100644
--- a/source/game/component.h
+++ b/source/game/component.h
@@ -25,8 +25,9 @@ public:
 	Handle<Entity> get_entity() const { return entity; }
 };
 
-template<typename T>
-class BufferedComponent: public Component
+template<typename T, typename Base = Component>
+	requires std::is_base_of_v<Component, Base>
+class BufferedComponent: public Base
 {
 public:
 	using Data = T;
@@ -38,7 +39,7 @@ private:
 	bool written = false;
 
 protected:
-	BufferedComponent(Handle<Entity> e): Component(e) { }
+	using Base::Base;
 
 	const T &read() const;
 	T &write();
@@ -51,8 +52,9 @@ public:
 	bool was_written() const { return written; }
 };
 
-template<typename T>
-const T &BufferedComponent<T>::read() const
+template<typename T, typename Base>
+	requires std::is_base_of_v<Component, Base>
+const T &BufferedComponent<T, Base>::read() const
 {
 #ifdef DEBUG
 	AccessGuard::get_instance().check<AccessGuard::Read<T>>();
@@ -60,8 +62,9 @@ const T &BufferedComponent<T>::read() const
 	return data[read_index&1];
 }
 
-template<typename T>
-T &BufferedComponent<T>::write()
+template<typename T, typename Base>
+	requires std::is_base_of_v<Component, Base>
+T &BufferedComponent<T, Base>::write()
 {
 #ifdef DEBUG
 	AccessGuard::get_instance().check<AccessGuard::Write<T>>();
-- 
2.45.2