format_error_bullets {rlang}

Format bullets for error messages

Description

format_error_bullets() takes a character vector and returns a single string (or an empty vector if the input is empty). The elements of the input vector are assembled as a list of bullets, depending on their names:

• Unnamed elements are unindented. They act as titles or subtitles.

• Elements named "*" are bulleted with a cyan "bullet" symbol.

• Elements named "i" are bulleted with a blue "info" symbol.

• Elements named "x" are bulleted with a red "cross" symbol.

• Elements named "v" are bulleted with a green "tick" symbol.

• Elements named "!" are bulleted with a yellow "warning" symbol.

• Elements named ">" are bulleted with an "arrow" symbol.

• Elements named " " start with an indented line break.

For convenience, if the vector is fully unnamed, the elements are formatted as "*" bullets.

The bullet formatting for errors follows the idea that sentences in error messages are best kept short and simple. The best way to present the information is in the cnd_body() method of an error conditon as a bullet list of simple sentences containing a single clause. The info and cross symbols of the bullets provide hints on how to interpret the bullet relative to the general error issue, which should be supplied as cnd_header().

Usage

format_error_bullets(x)

Arguments

x

A named character vector of messages. Named elements are prefixed with the corresponding bullet. Elements named with a single space " " trigger a line break from the previous bullet.

Examples

# All bullets
writeLines(format_error_bullets(c("foo", "bar")))

# This is equivalent to
writeLines(format_error_bullets(set_names(c("foo", "bar"), "*")))

# Supply named elements to format info, cross, and tick bullets
writeLines(format_error_bullets(c(i = "foo", x = "bar", v = "baz", "*" = "quux")))

# An unnamed element breaks the line
writeLines(format_error_bullets(c(i = "foo\nbar")))

# A " " element breaks the line within a bullet (with indentation)
writeLines(format_error_bullets(c(i = "foo", " " = "bar")))