1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/good-lambda.cpp	Wed Oct 30 22:08:49 2024 +0100
     1.3 @@ -0,0 +1,68 @@
     1.4 +/**
     1.5 + * cpp-finally
     1.6 + * Copyright © 2024 František Kučera (Frantovo.cz, GlobalCode.info)
     1.7 + *
     1.8 + * This program is free software: you can redistribute it and/or modify
     1.9 + * it under the terms of the GNU General Public License as published by
    1.10 + * the Free Software Foundation, version 3 of the License.
    1.11 + *
    1.12 + * This program is distributed in the hope that it will be useful,
    1.13 + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    1.14 + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    1.15 + * GNU General Public License for more details.
    1.16 + *
    1.17 + * You should have received a copy of the GNU General Public License
    1.18 + * along with this program. If not, see <http://www.gnu.org/licenses/>.
    1.19 + */
    1.20 +
    1.21 +#include <iostream>
    1.22 +#include <exception>
    1.23 +#include <functional>
    1.24 +
    1.25 +class Finally {
    1.26 +private:
    1.27 +	Finally(const Finally&) = delete;
    1.28 +	Finally& operator=(const Finally&) = delete;
    1.29 +public:
    1.30 +	std::function<void(void) > fx;
    1.31 +
    1.32 +	Finally(std::function<void(void) > fx) : fx(fx) {
    1.33 +	}
    1.34 +
    1.35 +	virtual ~Finally() {
    1.36 +		fx();
    1.37 +	}
    1.38 +};
    1.39 +
    1.40 +void fxThrowing(bool fail, void* data) {
    1.41 +	std::cout << "  doing something with data " << data << std::endl;
    1.42 +	if (fail) throw std::logic_error("error from fxThrowing()");
    1.43 +}
    1.44 +
    1.45 +void fxAllocating(bool fail) {
    1.46 +	void* buf = malloc(486);
    1.47 +	void* tmp = malloc(123);
    1.48 +	std::cout << "  allocated memory at: " << buf << std::endl;
    1.49 +	std::cout << "  allocated memory at: " << tmp << std::endl;
    1.50 +
    1.51 +	Finally finally([&]() {
    1.52 +		free(buf);
    1.53 +		free(tmp);
    1.54 +		std::cout << "  freed memory at: " << buf << std::endl;
    1.55 +		std::cout << "  freed memory at: " << tmp << std::endl;
    1.56 +	});
    1.57 +
    1.58 +	fxThrowing(fail, buf);
    1.59 +	fxThrowing(fail, tmp);
    1.60 +}
    1.61 +
    1.62 +int main(int argc, char** argv) {
    1.63 +	bool fail = argc == 2 && std::string("fail") == argv[1];
    1.64 +	const char* name = "good-lambda";
    1.65 +	std::cout << name << " (fail=" << fail << ")\n";
    1.66 +	try {
    1.67 +		fxAllocating(fail);
    1.68 +	} catch (const std::exception& e) {
    1.69 +		std::cout << "  caught exception: " << e.what() << std::endl;
    1.70 +	}
    1.71 +}