Control How Progress is Reported

handlers(
  ...,
  append = FALSE,
  on_missing = c("error", "warning", "ignore"),
  default = handler_txtprogressbar,
  global = NULL
)

Arguments

...: One or more progression handlers. Alternatively, this functions accepts also a single vector of progression handlers as input. If this vector is empty, then an empty set of progression handlers will be set.
append: (logical) If FALSE, the specified progression handlers replace the current ones, otherwise appended to them.
on_missing: (character) If "error", an error is thrown if one of the progression handlers does not exists. If "warning", a warning is produces and the missing handlers is ignored. If "ignore", the missing handlers is ignored.
default: The default progression calling handler to use if none are set.
global: If TRUE, then the global progression handler is enabled. If FALSE, it is disabled. If NA, then TRUE is returned if it is enabled, otherwise FALSE. Argument global must not used with other arguments.

Value

(invisibly) the previous list of progression handlers set. If no arguments are specified, then the current set of progression handlers is returned. If global is specified, then TRUE is returned if the global progression handlers is enabled, otherwise false.

Details

This function provides a convenient alternative for getting and setting option progressr.handlers.

For package developers

IMPORTANT: Setting progression handlers is a privilege that should be left to the end user. It should not be used by R packages, which only task is to signal progress updates, not to decide if, when, and how progress should be reported.

If you have to set or modify the progression handlers inside a function, please make sure to undo the settings afterward. If not, you will break whatever progression settings the user already has for other purposes used elsewhere. To undo you settings, you can do:

old_handlers <- handlers(c("beepr", "progress"))
on.exit(handlers(old_handlers), add = TRUE)

Configuring progression handling during R startup

A convenient place to configure the default progression handler and to enable global progression reporting by default is in the ~/.Rprofile startup file. For example, the following will (i) cause your interactive R session to use global progression handler by default, and (ii) report progress via the progress package when in the terminal and via the RStudio Jobs progress bar when in the RStudio Console. handler_txtprogressbar, other whenever using the RStudio Console, add the following to your ~/.Rprofile startup file: