Apple’s Grand Central Dispatch concurrency library has dispatch_once [0], which does something similar. It relies on non-standard “block” extensions to C, which

Apple’s Grand Central Dispatch concurrency library has dispatch_once [0], which does something similar. It relies on non-standard “block” extensions to C, which are a way of defining lambda functions, and in practice you only see it used in Apple platforms. [0] https://developer.apple.com/documentation/dispatch/1447169-dispatch_once https://developer.apple.com/documentation/dispatch/1447169-d...