topic-condition-customisation: Customising condition messages

In hadley/rlang: Functions for Base Types and Core R and 'Tidyverse' Features

Customising condition messages

Description

Various aspects of the condition messages displayed by abort(), warn(), and inform() can be customised using options from the cli package.

Turning off unicode bullets

By default, bulleted lists are prefixed with unicode symbols:

rlang::abort(c(
  "The error message.",
  "*" = "Regular bullet.",
  "i" = "Informative bullet.",
  "x" = "Cross bullet.",
  "v" = "Victory bullet.",
  ">" = "Arrow bullet."
))
#> Error:
#> ! The error message.
#> • Regular bullet.
#> ℹ Informative bullet.
#> ✖ Cross bullet.
#> ✔ Victory bullet.
#> → Arrow bullet.

Set this option to use simple letters instead:

options(cli.condition_unicode_bullets = FALSE)

rlang::abort(c(
  "The error message.",
  "*" = "Regular bullet.",
  "i" = "Informative bullet.",
  "x" = "Cross bullet.",
  "v" = "Victory bullet.",
  ">" = "Arrow bullet."
))
#> Error:
#> ! The error message.
#> * Regular bullet.
#> i Informative bullet.
#> x Cross bullet.
#> v Victory bullet.
#> > Arrow bullet.

Changing the bullet symbols

You can specify what symbol to use for each type of bullet through your cli user theme. For instance, here is how to uniformly use * for all bullet kinds:

options(cli.user_theme = list(
  ".cli_rlang .bullet-*" = list(before = "* "),
  ".cli_rlang .bullet-i" = list(before = "* "),
  ".cli_rlang .bullet-x" = list(before = "* "),
  ".cli_rlang .bullet-v" = list(before = "* "),
  ".cli_rlang .bullet->" = list(before = "* ")
))

rlang::abort(c(
  "The error message.",
  "*" = "Regular bullet.",
  "i" = "Informative bullet.",
  "x" = "Cross bullet.",
  "v" = "Victory bullet.",
  ">" = "Arrow bullet."
))
#> Error:
#> ! The error message.
#> * Regular bullet.
#> * Informative bullet.
#> * Cross bullet.
#> * Victory bullet.
#> * Arrow bullet.

If you want all the bullets to be the same, including the leading bullet, you can achieve this using the bullet class:

options(cli.user_theme = list(
  ".cli_rlang .bullet" = list(before = "* ")
))

rlang::abort(c(
  "The error message.",
  "*" = "Regular bullet.",
  "i" = "Informative bullet.",
  "x" = "Cross bullet.",
  "v" = "Victory bullet.",
  ">" = "Arrow bullet."
))
#> Error:
#> * The error message.
#> * Regular bullet.
#> * Informative bullet.
#> * Cross bullet.
#> * Victory bullet.
#> * Arrow bullet.

Changing the foreground and background colour of error calls

When called inside a function, abort() displays the function call to help contextualise the error:

splash <- function() {
  abort("Can't splash without water.")
}

splash()
#> Error in `splash()`:
#> ! Can't splash without water.

The call is formatted with cli as a code element. This is not visible in the manual, but code text is formatted with a highlighted background colour by default. When this can be reliably detected, that background colour is different depending on whether you're using a light or dark theme.

You can override the colour of code elements in your cli theme. Here is my personal configuration that fits well with the colour theme I currently use in my IDE:

options(cli.user_theme = list(
  span.code = list(
    "background-color" = "#3B4252",
    color = "#E5E9F0"
  )
))

hadley/rlang documentation built on Dec. 17, 2024, 3:26 a.m.