Archive.png This article or section documents something not included in the current version of Scratch (3.0). It is only useful from a historical perspective.
Forever If ()
2.0 Forever If ().png
Category Control
Type C
Introduced in 1.0
Removed in 2.0

The Forever If () block was a Control block and a C block. The block would continuously check its Boolean condition. If the condition is true, the code held inside the block would run, and then the script continues, but if the condition is false, nothing would happen until it becomes true again. The block continuously runs in a loop; in fact, this block worked just like the If () block placed into the Forever block. After being removed, this block is replaced with its workaround.

Workaround

Main article: List of Block Workarounds

This block can be simulated with the following code:

forever
 if <...> then
  . . .
 end
end

or

forever
 wait until <...>
  . . .
end

or

forever
 repeat until <not <...>>
  . . .
 end
end

In Scratch 2.0, this block is automatically replaced with the first workaround.

Removal

Due to the block's simplicity to recreate, that it has less functionality than the replication (you cannot stack multiple If () blocks inside the Forever If () block), and that new Scratchers sometimes confuse it with the Repeat Until () block, there had been many campaigns to remove the block.[1][2] Eventually in 2.0, the block was removed. The block had an advantage, though: it runs some milliseconds faster than its replication, so it could be used to combat extreme lag.

Despite the simple workaround, multiple users have suggested the block be brought back,[3][4] because it seems more natural to use for those newer to programming.[5]

Using the workaround gives an advantage too — you can place multiple If () statements (and If () Then, Else statements, and even other blocks) in the Forever loop. An example:

forever
 if <key [1 v] pressed?> then
  set [Page v] to (1)
 end
 if <key [2 v] pressed?> then
  set [Page v] to (2)
 end
 if <key [space v] pressed?> then
  broadcast [Render v]
 end
end

Example Uses

Some common uses, however, were:

  • Reducing lag
forever if <(size) > [100]> :: control
...//laggy script
when gf clicked
forever if <loud?::sensing> :: control
say [Shh... do not wake anyone up.]
  • Simple cases where there only needed to be one If () block in a Forever block, so the Forever If () was used instead
forever if <(x position) > [10]> :: control
hide

See Also


References

  1. ar-topic:25927
  2. http://suggest.scratch.mit.edu/forums/60449-suggestions/suggestions/1395003-delete-forever-if
  3. http://scratch.mit.edu/discuss/topic/9989/
  4. http://scratch.mit.edu/discuss/topic/20438/?page=1
  5. http://scratch.mit.edu/discuss/topic/30138/