init cpp repo

main.cxx

@@ -0,0 +1,54 @@
+import <print>;
+import <type_traits>;
+
+template <bool param1 = false, bool param2 = false>
+struct Builder;
+template <bool enabled>
+struct BuildMixin {};
+
+template <>
+struct BuildMixin<true> {
+  auto build(this auto&& self) { return self.p1 + self.p2; }
+};
+
+template <bool enabled>
+struct Param1Mixin {};
+
+template <>
+struct Param1Mixin<false> {
+  auto fill_param1(this auto&& self) {
+    self.p1 = 1;
+    return Builder<true, std::remove_reference_t<decltype(self)>::param2_v>(
+        self);
+  }
+};
+
+template <bool enabled>
+struct Param2Mixin {};
+
+template <>
+struct Param2Mixin<false> {
+  auto fill_param2(this auto&& self) {
+    self.p2 = 1;
+    return Builder<std::remove_reference_t<decltype(self)>::param1_v, true>(
+        self);
+  }
+};
+
+template <bool param1, bool param2>
+struct Builder : BuildMixin<param1 && param2>,
+                 Param1Mixin<param1>,
+                 Param2Mixin<param2> {
+  const constinit static auto param1_v = param1;
+  const constinit static auto param2_v = param2;
+  int p1;
+  int p2;
+  Builder() : p1(0), p2(0) {}
+  Builder(auto&& other) : p1(other.p1), p2(other.p2) {}
+};
+
+auto main() -> int {
+  Builder builder;
+  auto ret = builder.fill_param1().fill_param2().build();
+  std::println("{}", ret);
+}