Format messages and warnings — format

Inserts line breaks into a longer message or warning string. Line length is adjusted to maximum length of the console, if the width can be accessed. By default, new lines are indented by two spaces.

format_alert() is a wrapper that combines formatting a string with a call to message(), warning() or stop(). By default, format_alert() creates a message(). format_warning() and format_error() change the default type of exception to warning() and stop(), respectively.

Usage

format_message(
  string,
  ...,
  line_length = 0.9 * getOption("width", 80),
  indent = "  "
)

format_alert(
  string,
  ...,
  line_length = 0.9 * getOption("width", 80),
  indent = "  ",
  type = "message",
  call. = FALSE
)

format_warning(...)

format_error(...)

Arguments

string: A string.
...: Further strings that will be concatenated as indented new lines.
line_length: Numeric, the maximum length of a line. The default is 90% of the width of the console window.
indent: Character vector. If further lines are specified in ..., a user-defined string can be specified to indent subsequent lines. Defaults to " " (two white spaces), hence for each start of the line after the first line, two white space characters are inserted.
type: Type of exception alert to raise. Can be "message" for message(), "warning" for warning(), or "error" for stop().
call.: Logical. Indicating if the call should be included in the the error message. This is usually confusing for users when the function producing the warning or error is deep within another function, so the default is FALSE.

Value

For format_message(), a formatted string. For format_alert() and related functions, the requested exception, with the exception formatted using format_message().

Details

There is an experimental formatting feature implemented in this function. You can use following tags:

{.b text} for bold formatting
{.i text} to use italic font style
{.url www.url.com} formats the string as URL (i.e., enclosing URL in < and >, blue color and italic font style)
{.pkg packagename} formats the text in blue color.

This features has some limitations: it's hard to detect the exact length for each line when the string has multiple lines (after line breaks) and the string contains formatting tags. Thus, it can happen that lines are wrapped at an earlier length than expected. Furthermore, if you have multiple words in a format tag ({.b one two three}), a line break might occur inside this tag, and the formatting no longer works (messing up the message-string).

Examples

msg <- format_message("Much too long string for just one line, I guess!",
  line_length = 15
)
message(msg)
#> Much too long
#>   string for just
#>   one line, I
#>   guess!

msg <- format_message("Much too long string for just one line, I guess!",
  "First new line",
  "Second new line",
  "(both indented)",
  line_length = 30
)
message(msg)
#> Much too long string for just
#>   one line, I guess!
#>   First new line
#>   Second new line
#>   (both indented)

msg <- format_message("Much too long string for just one line, I guess!",
  "First new line",
  "Second new line",
  "(not indented)",
  line_length = 30,
  indent = ""
)
message(msg)
#> Much too long string for just
#>   one line, I guess!
#> First new line
#> Second new line
#> (not indented)

# Caution, experimental! See 'Details'
msg <- format_message(
  "This is {.i italic}, visit {.url easystats.github.io/easystats}",
  line_length = 30
)
message(msg)
#> This is italic, visit
#>   <easystats.github.io/easystats>

# message
format_alert("This is a message.")
#> This is a message.
format_alert("This is a warning.", type = "message")
#> This is a warning.

# error
try(format_error("This is an error."))
#> Error : This is an error.
# warning
format_warning("This is a warning.")
#> Warning: This is a warning.