make_spinner: Create a spinner

Description

Create a spinner

Usage

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

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.

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.

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())