Create scope_example.cpp

Author: robert-andrzejuk

examples/scope_example.cpp

@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <cstdlib>
+#include <experimental/scope>
+#include <iostream>
+#include <string_view>
+
+void print_exit_status(std::string_view name, bool exit_status, bool did_throw)
+{
+    std::cout << name << ":\n";
+    std::cout << "  Throwed exception  " << (did_throw ? "yes" : "no") << "\n";
+    std::cout << "  Exit status        " << (exit_status ? "finished" : "pending") << "\n\n";
+}
+
+// Randomly throw an exception (50% chance)
+void maybe_throw()
+{
+    if (std::rand() >= RAND_MAX / 2)
+        throw std::exception{};
+}
+
+int main()
+{
+    bool exit_status{false}, did_throw{false};
+
+    // Manual handling at "end of scope"
+    try
+    {
+        maybe_throw();
+        exit_status = true;
+    }
+    catch (...)
+    {
+        did_throw = true;
+    }
+    print_exit_status("Manual handling", exit_status, did_throw);
+
+    // Using scope_exit: runs on scope exit (success or exception)
+    exit_status = did_throw = false;
+    try
+    {
+        auto guard = std::experimental::scope_exit{[&] { exit_status = true; }};
+        maybe_throw();
+    }
+    catch (...)
+    {
+        did_throw = true;
+    }
+    print_exit_status("scope_exit", exit_status, did_throw);
+
+    // Using scope_fail: runs only if an exception occurs
+    exit_status = did_throw = false;
+    try
+    {
+        auto guard = std::experimental::scope_fail{[&] { exit_status = true; }};
+        maybe_throw();
+    }
+    catch (...)
+    {
+        did_throw = true;
+    }
+    print_exit_status("scope_fail", exit_status, did_throw);
+
+    // Using scope_success: runs only if no exception occurs
+    exit_status = did_throw = false;
+    try
+    {
+        auto guard = std::experimental::scope_success{[&] { exit_status = true; }};
+        maybe_throw();
+    }
+    catch (...)
+    {
+        did_throw = true;
+    }
+    print_exit_status("scope_success", exit_status, did_throw);
+}