Re: Fwd: overlay face property not used for after-string property

[bojohan+news@dd.chalmers.se (Johan Bockgård)]

Joe Wells <jbw@macs.hw.ac.uk> writes:

> Also, fixing this issue this way leaves behind the difficulty of
> adding a face property manually to a property string (before-string,
> after-string, or display) which already has face properties.

In font-lock.el we find

      ;;; Additional text property functions.

      ;; The following text property functions should be builtins.  This
      ;; means they should be written in C and put with all the other text
      ;; property functions.  In the meantime, those that are used by
      ;; font-lock.el are defined in Lisp below and given a `font-lock-'
      ;; prefix.  Those that are not used are defined in Lisp below and
      ;; commented out.  sm.

      (defun font-lock-prepend-text-property ([...])
        "Prepend to one property of the text from START to END.
      Arguments PROP and VALUE specify the property and value to prepend
      to the value already in place.  The resulting property values are
      always lists.  Optional argument OBJECT is the string or buffer
      containing the text."
      [...]



(let ((s (propertize "abc" 'face 'bar)))
  (font-lock-prepend-text-property 1 2 'face 'foo s)
  s)

  =>  #("abc" 0 1 (face bar) 1 2 (face (foo bar)) 2 3 (face bar))

-- 
Johan Bockgård