From: Keith David Bershatsky <esq@lawlist.com>
To: Emacs Devel <emacs-devel@gnu.org>
Subject: Adding new variable for face-list in internal-make-lisp-face.
Date: Thu, 02 Nov 2017 20:50:47 -0700 [thread overview]
Message-ID: <m2h8ucm354.wl%esq@lawlist.com> (raw)
In implementing feature requests crosshairs (17684) and multiple fake cursors (22873), I thought it would be nifty to identify the background color (if applicable) associated with a tab ('\t') glyph code in the buffer-display-table. In doing so, I discovered that the Lisp function face-list is way too slow. Even after I ported the face-list function over to C, it was still way too slow. So, I tried my luck at adding a new variable in xfaces.c for the face-list and am setting it from within the function internal-make-lisp-face, like so:
Vface_list = Fcons (face, Vface_list);
and, it is done within the same section where we already have:
Vface_new_frame_defaults = Fcons (Fcons (face, global_lface),
Vface_new_frame_defaults);
Accessing the tab face in the face-list variable works just fine UNTIL I manually `eval-defun` on the `defface` for the tab face to change its background color. Thereafter, when I try to get information about that tab face in the face-list from within xdisp.c, I get:
Error during redisplay: (my-custom-face-attribute #<EMACS BUG: INVALID DATATYPE (MISC 0xc9ff) Save your buffers immediately and please report this bug> :background [frame information] default) signaled (error "Invalid face" #<EMACS BUG: INVALID DATATYPE (MISC 0xc9ff) Save your buffers immediately and please report this bug>)
Here is the gdb breakpoint information when I try to access that face (in the face-list variable) after manually changing the background color with eval-defun -- I get INVALID_LISP_OBJECT:
Breakpoint 3, Fmc_face_attribute (face=..., attribute=..., frame=...,
inherit=...) at xdisp.c:1119
1119 Lisp_Object value = Finternal_get_lisp_face_attribute (face, attribute, frame);
(gdb) pp face
#<INVALID_LISP_OBJECT 0x10013c199>
How can I properly implement a new face-list variable so that the lisp object will be valid after manually running `eval-defun` on a defface?
Thanks,
Keith
next reply other threads:[~2017-11-03 3:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-03 3:50 Keith David Bershatsky [this message]
2017-11-03 10:17 ` Adding new variable for face-list in internal-make-lisp-face Eli Zaretskii
-- strict thread matches above, loose matches on Subject: below --
2017-11-03 22:01 Keith David Bershatsky
2017-11-04 8:05 ` Eli Zaretskii
2017-11-04 6:56 Keith David Bershatsky
2017-11-04 8:13 ` Eli Zaretskii
2017-11-04 17:46 Keith David Bershatsky
2017-11-04 18:16 ` Eli Zaretskii
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