Rollback a Number of Activities — rollback • simmer

Activity for going backwards to a previous point in the trajectory. Useful to implement loops.

rollback(.trj, amount, times = Inf, check = NULL)

Arguments

.trj	the trajectory object.
amount	the amount of activities (of the same or parent trajectories) to roll back.
times	the number of repetitions until an arrival may continue.
check	a callable object (a function) which must return a boolean. If present, the `times` parameter is ignored, and the activity uses this function to check whether the rollback must be done or not.

Value

Returns the trajectory object.

Examples

## rollback a specific number of times
traj <- trajectory() %>%
  log_("hello!") %>%
  timeout(1) %>%
  rollback(2, 3)

simmer() %>%
  add_generator("hello_sayer", traj, at(0)) %>%
  run() %>% invisible
#> 0: hello_sayer0: hello!
#> 1: hello_sayer0: hello!
#> 2: hello_sayer0: hello!
#> 3: hello_sayer0: hello!

## custom check
env <- simmer()

traj <- trajectory() %>%
  set_attribute("var", 0) %>%
  log_(function()
    paste("attribute level is at:", get_attribute(env, "var"))) %>%
  set_attribute("var", 25, mod="+") %>%
  rollback(2, check=function() get_attribute(env, "var") < 100) %>%
  log_("done")

env %>%
  add_generator("dummy", traj, at(0)) %>%
  run() %>% invisible
#> 0: dummy0: attribute level is at: 0
#> 0: dummy0: attribute level is at: 25
#> 0: dummy0: attribute level is at: 50
#> 0: dummy0: attribute level is at: 75
#> 0: dummy0: done