diff -r 4502b1c7346d -r 64777e5b619f good-lambda.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/good-lambda.cpp	Wed Oct 30 22:08:49 2024 +0100
@@ -0,0 +1,68 @@
+/**
+ * cpp-finally
+ * Copyright © 2024 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <iostream>
+#include <exception>
+#include <functional>
+
+class Finally {
+private:
+	Finally(const Finally&) = delete;
+	Finally& operator=(const Finally&) = delete;
+public:
+	std::function<void(void) > fx;
+
+	Finally(std::function<void(void) > fx) : fx(fx) {
+	}
+
+	virtual ~Finally() {
+		fx();
+	}
+};
+
+void fxThrowing(bool fail, void* data) {
+	std::cout << "  doing something with data " << data << std::endl;
+	if (fail) throw std::logic_error("error from fxThrowing()");
+}
+
+void fxAllocating(bool fail) {
+	void* buf = malloc(486);
+	void* tmp = malloc(123);
+	std::cout << "  allocated memory at: " << buf << std::endl;
+	std::cout << "  allocated memory at: " << tmp << std::endl;
+
+	Finally finally([&]() {
+		free(buf);
+		free(tmp);
+		std::cout << "  freed memory at: " << buf << std::endl;
+		std::cout << "  freed memory at: " << tmp << std::endl;
+	});
+
+	fxThrowing(fail, buf);
+	fxThrowing(fail, tmp);
+}
+
+int main(int argc, char** argv) {
+	bool fail = argc == 2 && std::string("fail") == argv[1];
+	const char* name = "good-lambda";
+	std::cout << name << " (fail=" << fail << ")\n";
+	try {
+		fxAllocating(fail);
+	} catch (const std::exception& e) {
+		std::cout << "  caught exception: " << e.what() << std::endl;
+	}
+}