Tengo by Example: Closures

Closures

Wikipedia: Closure
Tengo supports anonymous functions, which can form closures. Closures are functions that "capture" variables from their outer scope.

fmt := import("fmt")

This function intSeq returns another function, which we define anonymously in the body of intSeq. The returned function closes over the variable i to form a closure.

intSeq := func() {
    i := 0
    return func() {
        i++
        return i
    }
}

We call intSeq, assigning the result (a function) to nextInt. This function value captures its own i value, which will be updated each time we call nextInt.

nextInt := intSeq()

See the effect of the closure by calling nextInt a few times.

fmt.println(nextInt())
fmt.println(nextInt())
fmt.println(nextInt())

To confirm that the state is unique to that particular function, create and test a new one.

newInts := intSeq()
fmt.println(newInts())

try it

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