Create a spinner

Usage

make_spinner(
  which = NULL,
  stream = "auto",
  template = "{spin}",
  static = c("dots", "print", "print_line", "silent")
)

Arguments

which

The name of the chosen spinner. If NULL, then the default is used, which can be customized via the cli.spinner_unicode, cli.spinner_ascii and cli.spinner options. (The latter applies to both Unicode and ASCII displays. These options can be set to the name of a built-in spinner, or to a list that has an entry called frames, a character vector of frames.

stream

The stream to use for the spinner. Typically this is standard error, or maybe the standard output stream. It can also be a string, one of "auto", "message", "stdout", "stderr". "auto" will select stdout() if the session is interactive and there are no sinks, otherwise it will select stderr().

template

A template string, that will contain the spinner. The spinner itself will be substituted for {spin}. See example below.

static

What to do if the terminal does not support dynamic displays:

"dots": show a dot for each $spin() call.
"print": just print the frames of the spinner, one after another.
"print_line": print the frames of the spinner, each on its own line.
"silent" do not print anything, just the template.

Value

A cli_spinner object, which is a list of functions. See its methods below.

cli_spinner methods:

$spin(): output the next frame of the spinner.
$finish(): terminate the spinner. Depending on terminal capabilities this removes the spinner from the screen. Spinners can be reused, you can start calling the $spin() method again.

All methods return the spinner object itself, invisibly.

The spinner is automatically throttled to its ideal update frequency.

Examples

Default spinner

sp1 <- make_spinner()
fun_with_spinner <- function() {
  lapply(1:100, function(x) { sp1$spin(); Sys.sleep(0.05) })
  sp1$finish()
}
ansi_with_hidden_cursor(fun_with_spinner())

Spinner with a template

sp2 <- make_spinner(template = "Computing {spin}")
fun_with_spinner2 <- function() {
  lapply(1:100, function(x) { sp2$spin(); Sys.sleep(0.05) })
  sp2$finish()
}
ansi_with_hidden_cursor(fun_with_spinner2())

Custom spinner

sp3 <- make_spinner("simpleDotsScrolling", template = "Downloading {spin}")
fun_with_spinner3 <- function() {
  lapply(1:100, function(x) { sp3$spin(); Sys.sleep(0.05) })
  sp3$finish()
}
ansi_with_hidden_cursor(fun_with_spinner3())