ansi(Class, Fmt, Args)

ansi(Class, Fmt, Args, Ctx)

Write Fmt/Args using the attributes of Class. As the element ends with a full reset, the 4th argument version re-installs the decoration of the message as a whole afterwards.

url(Location)

url(URL, Label)

Write a hyperlink. See ansi_hyperlink/2,3. Label is an atom or string, a Format-Args pair or an ansi/3 or ansi/4 term. The latter combines a hyperlink with a style class.

begin(Class, Ctx)

end(Ctx)

Decorate the message as a whole. See below.

nl(Ctx),flush(Ctx)

End a line. If the message has a background colour, the remainder of the line is painted using `\e[K` (Erase in Line) such that the coloured block extends to the right margin.

eol(Ctx)

As above, but also reset the attributes: this ends the decorated part of the line. A message uses this for its last line if that line is not ended using nl. Resetting matters because a terminal that scrolls while a background colour is in effect paints the newly exposed line with it.

Ctx is the message context. It is created by the handler for begin/2 as a term

ansi(Reset, ReInstall, EraseEol)

where Reset is the sequence written by end/1, ReInstall is a Format-Args pair that re-installs the attributes of the message and EraseEol is the sequence that paints the remainder of the line or the empty atom. Callers must treat Ctx as opaque. It is left unbound if Stream is not a terminal, if the color_term flag is false or if the message has no attributes. All handlers that use Ctx therefore fail if it is unbound, which makes print_message_lines/3 fall back to writing plain text.