cleanup examples

develop/manuals/meta_examples/ucast_example.cpp

@@ -0,0 +1,54 @@
+/*******************************************************************************
+ * This file is part of the "https://github.com/blackmatov/meta.hpp"
+ * For conditions of distribution and use, see copyright notice in LICENSE.md
+ * Copyright (C) 2021-2024, by Matvey Cherevko (blackmatov@gmail.com)
+ ******************************************************************************/
+
+#include <meta.hpp/meta_all.hpp>
+
+#include <doctest/doctest.h>
+#include <fmt/core.h>
+
+namespace
+{
+    // we should add META_HPP_ENABLE_POLY_INFO macro inside every class
+    // to add polymorphic information to our inheritance hierarchy
+
+    // after this we will be able to use the library's polymorphic functions
+    // like `ucast` or `resolve_type(T&&)`
+
+    struct A {
+        virtual ~A() = default;
+        META_HPP_ENABLE_POLY_INFO()
+    };
+
+    struct B {
+        virtual ~B() = default;
+        META_HPP_ENABLE_POLY_INFO()
+    };
+
+    struct C : A, B {
+        META_HPP_ENABLE_POLY_INFO(A, B)
+    };
+}
+
+TEST_CASE("meta/meta_examples/ucast") {
+    namespace meta = meta_hpp;
+
+    C c{};
+
+    A& a = c;
+    B& b = c;
+
+    // functions `ucast` and `resolve_type(T&&)` rely on polymorphic information
+    // are provided in META_HPP_ENABLE_POLY_INFO macro
+
+    // we can use polymorphic type resolving to get most derived class type
+    CHECK(meta::resolve_type(a) == meta::resolve_type<C>());
+
+    // and cast our pointers and references like dynamic_cast does
+    CHECK(&c == &meta::ucast<C&>(a));
+
+    // `ucast` supports cross casts, multiple and virtual inheritance as well
+    CHECK(&a == meta::ucast<A*>(&b));
+}