# waitfor setting (proc)

Source: https://ref.dm-lang.org/proc/set/waitfor

By default, procs that sleep usually expect their callers to wait for them to finish, so the callers must sleep as well. Using `set waitfor=0` will disable that behavior, causing any sleep to return control to the caller immediately.

## Example

```dm
mob/proc/LongLoop()
   set waitfor = 0
   while(1)
      UpdateAI()
      // proc will return to caller here
      sleep(1)
```

This setting will also dictate what happens if a callee sleeps. Consider an example where proc A calls proc B which calls proc C, and proc B has `waitfor` set to 0. When proc C sleeps, proc B will also sleep, but proc A will continue running as if proc B returned early. The `.` var currently in proc B will be used as its return value to A. When proc C wakes up and finishes, it will wake up proc B, but now B's return value will be ignored since A is no longer waiting for it.

In older versions, the [`New` proc](https://ref.dm-lang.org/datum/proc/New.md) always had `waitfor` set to 0 by default, but this was later changed. Now 1 is always the default, so setting `waitfor` to 1 will result in a warning that it is no longer necessary.

### See also
- [sleep proc](https://ref.dm-lang.org/proc/sleep.md)
- [spawn proc](https://ref.dm-lang.org/proc/spawn.md)
- [. var (proc)](https://ref.dm-lang.org/proc/var/dot.md)