Explicitly limit a scope

A bare block creates an anonymous lexical scope. It runs exactly once and produces no value.

struct Counter {
    var value:int
    func increment() { self.value++ }
}

func main() {
    var counter = Counter(value:0)
    {
        let increment:func() = counter.increment
        increment()
    }

    counter.value += 1
    print(counter.value)
}

Here, the scope releases the borrow retained by the bound method before the next direct access to counter. Its variables disappear after }, and their cleanup runs before every normal or transferred exit from the block.

Successive scopes may reuse the same local names. The block has no trailing semicolon. It does not intercept control flow: break and continue still target the nearest enclosing loop, while return always exits the function.

Back to execution control · Understand callback borrows