examples -> example

example/throw_error_handler.cpp

@@ -0,0 +1,68 @@
+// Copyright (c) 2018-2025 Jean-Louis Leroy
+// Distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE_1_0.txt
+// or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// tag::example[]
+#include <iostream>
+
+#include <boost/openmethod/default_registry.hpp>
+
+struct Animal {
+    virtual ~Animal() = default;
+};
+
+struct Cat : Animal {};
+struct Dog : Animal {};
+
+namespace bom = boost::openmethod;
+
+struct throw_if_not_implemented : bom::policies::error_handler {
+    template<class Registry>
+    struct fn {
+        static auto error(const bom::openmethod_error&) -> void {
+        }
+
+        static auto error(const bom::not_implemented_error& err) -> void {
+            throw err;
+        }
+    };
+};
+
+struct custom_registry : bom::default_registry::with<throw_if_not_implemented> {
+};
+
+#define BOOST_OPENMETHOD_DEFAULT_REGISTRY custom_registry
+
+#include <boost/openmethod.hpp>
+#include <boost/openmethod/compiler.hpp>
+
+using boost::openmethod::virtual_ptr;
+
+BOOST_OPENMETHOD_CLASSES(Animal, Cat, Dog);
+
+BOOST_OPENMETHOD(trick, (std::ostream&, virtual_ptr<Animal>), void);
+
+BOOST_OPENMETHOD_OVERRIDE(
+    trick, (std::ostream & os, virtual_ptr<Dog> /*dog*/), void) {
+    os << "spin\n";
+}
+
+auto main() -> int {
+    bom::initialize();
+
+    Cat felix;
+    Dog hector, snoopy;
+    std::vector<Animal*> animals = {&hector, &felix, &snoopy};
+
+    for (auto animal : animals) {
+        try {
+            trick(std::cout, *animal);
+        } catch (bom::not_implemented_error&) {
+            std::cout << "not implemented\n";
+        }
+    }
+
+    return 0;
+}
+// end::example[]