Eng:Forever (block)

The Forever block is a Control block and a C block. Blocks held inside this block will be in a loop just like the Repeat  block and the Repeat Until  block, except that the loop never ends (unless the stop sign is clicked, the Stop All block is activated, or the stop script block is activated within the loop). Due to this infinite loop, the block has no bump at the bottom; having a bump would be pointless, as the blocks below it would never be activated.

This block has a slight delay, so for optimum speed of execution, single frame block stacks should be used.



Example Uses
The block is one of the most commonly used blocks in Scratch because there are a lot of cases when an infinite loop is needed. Some common uses are:
 * Keeping a sprite at another's location

forever go to [Sprite1 v]


 * A music loop

forever play sound [Battle theme v] until done


 * Animations (such as a waving hand)

forever repeat (12) turn left (3) degrees end repeat (12) turn right (3) degrees

Workaround
This block can be replicated in two ways: With a boolean statement that will never be true, or through recursion.

With the boolean method, the Repeat Until block is used, along with the boolean statement. There are many that will never be true, including: <[1] = [-1]> <[a] = [b]> <(timer) = [-1]> >>

A full workaround:

repeat until <[1] = [-1]> . ..

One method that does not involve false boolean statements is tail recursion. Tail recursion can be created by a script broadcasting the broadcast needed to start it, thus repeatedly running the script:

when I receive [Recursion v] .. . broadcast [Recursion v]

This has some benefits to making projects. For example, the script is helpful since it can be used to create fractals.

This also works:

repeat ([10^ v] of (309)) . . . end

This requires an operator that reports "Infinity", like:

([10^ v] of (309)) ([e^ v] of (1000)) (join [Infinity] [])

All of these will work in the last workaround.