var m: std.Thread.Mutex = .{}; fn good() !void { m.lock(); defer m.unlock(); try f(); if (!everything_ok()) return; }

var m: std.Thread.Mutex = .{}; fn good() !void { m.lock(); defer m.unlock(); try f(); if (!everything_ok()) return; } It's still the RAII pattern. The explicit call to deinitialization does not disqualify it. I can overcomplicate it with a LockGuard class too: const LockGuard = struct { mutex: *std.Thread.Mutex, fn init(mutex: *std.Thread.Mutex) !LockGuard { mutex.lock(); return .{ .mutex = mutex, }; } fn deinit(lg: *LockGuard) void { lg.mutex.unlock(); } }; fn good() !void { var lk = try LockGuard.init(&m); defer lk.deinit(); try f(); if (!everything_ok()) return; } In this case it demonstrates an improvement over C++, which is what happens if an error happens during a constructor. In C++ throwing an exception in a constructor is essentially UB; in zig it's a regular function call just like anything else.