main-window: further work

1 files changed, 32 insertions, 9 deletions

diff --git a/main-window/mixin-traits.cpp b/main-window/mixin-traits.cpp
index ea8e9bc8..5dc2efd8 100644
--- a/main-window/mixin-traits.cpp
+++ b/main-window/mixin-traits.cpp
@@ -1,22 +1,27 @@
-//#define MIXIN_TRAIT_TESTS
+#define MIXIN_TRAIT_TESTS
 
 #ifdef MIXIN_TRAIT_TESTS
 #   include "mixin-traits.hpp"
 
+// the `impl' class provides a cast template through the CRTP pattern.
+// mixins don't do direct inheritance on themselves,
+// that's what mixin_traits::depends is for.
+
 namespace mixins::traits_detail {
 
 struct A {};
-struct B : A {};
+struct B {};
 struct C {};
+struct D {};
 
-template<> struct mixin_traits<B>
+template<> struct mixin_traits<A>
 {
-    using depends = tuple<A>;
+    using depends = tuple<>;
 };
 
-template<> struct mixin_traits<A>
+template<> struct mixin_traits<B>
 {
-    using depends = tuple<>;
+    using depends = tuple<A>;
 };
 
 template<> struct mixin_traits<C>
@@ -24,13 +29,31 @@ template<> struct mixin_traits<C>
     using depends = tuple<A>;
 };
 
+template<> struct mixin_traits<D>
+{
+    using depends = tuple<C>;
+};
+
 extern void test1();
 
 void test1()
 {
-    //impl<C> fail1;
-    impl<B> ok1;
-    impl<A> ok2;
+    struct U : B, A {};
+    struct V : D {};
+    struct W : C, A {};
+    struct Q : virtual W, virtual D {};
+
+#if 0
+    (void)impl<Q, W>();     // W not a mixin
+    (void)impl<V, A>();     // A
+    (void)impl<V, D>();     // D => C => A
+    (void)impl<V, D>();     // D => C => A
+    (void)impl<W, C, B>();  // B
+#else
+    (void)impl<U, B>();
+    (void)impl<W, C>();
+    (void)impl<Q, D, A>();
+#endif
 }
 
 } // ns mixins::traits_detail