Pin is a smart pointer that prevents memory movement to ensure async functions can safely resume execution.
Pin is a smart pointer that prevents a value from being moved, which is required for async functions to safely resume execution on the same memory address. Without Pin, the compiler cannot guarantee that a future's internal state remains valid after it is suspended and resumed by the executor.
use std::pin::Pin;
// Pin ensures the value at the pointer cannot be moved
let pinned: Pin<Box<dyn Future>> = Box::pin(async { /* code */ });
Pin is a safety lock that tells the computer, "Do not move this data to a different memory address." It is essential for async code because async functions pause and resume; if the data moved while paused, the function would crash when it tried to resume. Think of it like pinning a map to a wall so you don't accidentally move it while you are looking at it.