encapsulate: Encapsulate Function Calls

In mlr3misc: Helper Functions for 'mlr3'

Encapsulate Function Calls

Description

Evaluates a function, capturing conditions and measuring elapsed time. There are currently five modes:

• "none": Runs the call in the current session. Conditions are signaled normally; no log is kept. Works well together with traceback().

• "try": Like "none", but catches errors and writes them to the log. Warnings and messages are still signaled.

• "evaluate": Uses evaluate to capture errors, warnings, and messages into the log. Printed output is lost.

• "callr": Uses callr to run the function in a fresh R session. Errors, warnings, and messages are captured into the log; printed output is lost. Protects the calling session from segfaults at the cost of session startup overhead. The RNG state is propagated back to the calling session after evaluation.

• "mirai": Uses mirai to run the function on a daemon. Errors, warnings, and messages are captured into the log; printed output is lost. The daemon can be pre-started via daemons(1); if none is running, a new session is started per call. Offers similar safety to "callr" with lower overhead when a daemon is reused across calls. The RNG state is propagated back to the calling session after evaluation.

Usage

encapsulate(
  method,
  .f,
  .args = list(),
  .opts = list(),
  .pkgs = character(),
  .seed = NA_integer_,
  .timeout = Inf,
  .compute = "default"
)

Arguments

method	(character(1)) One of "none", "try", "evaluate", "callr", or "mirai".
.f	(⁠function()⁠) Function to call.
.args	(list()) Named list of arguments passed to .f.
.opts	(named list()) Options to set via options() before calling .f. Restored on exit.
.pkgs	(character()) Packages to load via requireNamespace() before calling .f.
.seed	(integer(1)) Random seed set via set.seed() before calling .f. If NA (default), the seed is not changed; for "callr" and "mirai" modes the current RNG state is forwarded instead.
.timeout	(numeric(1)) Timeout in seconds (Inf for no limit). Uses setTimeLimit() for "none" and "evaluate"; passed natively to callr::r() and mirai::mirai() for the other modes.
.compute	(character(1)) Compute profile for "mirai" mode. Passed to mirai::mirai() as .compute.

Value

Named list() with three elements:

• "result": return value of .f, or NULL if an error was caught.

• "elapsed": elapsed time in seconds, measured via proc.time().

• "log": data.table() with columns "class" (ordered factor with levels "output", "warning", "error") and "condition" (list of condition objects). Messages are classified as "output" for historical reasons. Empty when no conditions were captured.

Examples

f = function(n) {
  message("hi from f")
  if (n > 5) {
    stop("n must be <= 5")
  }
  runif(n)
}

encapsulate("none", f, list(n = 1), .seed = 1)

if (requireNamespace("evaluate", quietly = TRUE)) {
  encapsulate("evaluate", f, list(n = 1), .seed = 1)
}

if (requireNamespace("callr", quietly = TRUE)) {
  encapsulate("callr", f, list(n = 1), .seed = 1)
}

mlr3misc documentation built on Feb. 26, 2026, 5:06 p.m.