Package: emacs;
Reported by: Keith David Bershatsky <esq <at> lawlist.com>
Date: Sun, 25 Jan 2015 07:21:02 UTC
Severity: normal
Tags: notabug
Found in version 25.0.50
Done: Stefan Kangas <stefan <at> marxist.se>
Bug is archived. No further changes may be made.
View this message in rfc822 format
From: Keith David Bershatsky <esq <at> lawlist.com> To: 19684 <at> debbugs.gnu.org Subject: bug#19684: 25.0.50; `this-command` is set to `nil` before `window-scroll-functions` hook runs. Date: Sat, 24 Jan 2015 23:19:48 -0800
To the extent that a user wishes to use the value of `this-command` within a function attached to the `window-scroll-functions` hook, a workaround is needed because the default value is `nil`. In other words, something at the C source code level is setting the value to `nil` before the `window-scroll-functions` hook runs. There are two (2) workarounds that I am aware of. 1. Expressly call `redisplay` at the tail end of the series of functions attached to the `post-command-hook`. Calling `redisplay` somehow prevents `this-command` from being reset to `nil` and the `window-scroll-functions` hook can then take advantage of the existing value of `this-command`. 2. Create a separate variable -- e.g., `my-this-command` and set the value within a function attached to the `post-command-hook`. Like so: (setq my-this-command this-command). And, then use the value of `my-this-command` within the function attached to the `window-scroll-functions` hook. The most reliable test I have discovered to pinpoint when the `window-scroll-functions` hook will activate is by having the following code within a function attached to the `post-command-hook`: (pos-visible-in-window-p (point) (get-buffer-window (current-buffer) (selected-frame))). If the result is `t`, then the `window-scroll-functions` hook will be activating. I do not see a visual difference between either of the two workarounds mentioned above, even though I would expect to see a flicker on the screen with the first workaround. However, there is no flicker. The second workaround is probably a safer bet. Although this bug report has been submitted with Emacs Trunk from October 1, 2014; the behavior is the same with Emacs Trunk built on January 1, 2015. Thanks, Keith ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; In GNU Emacs 25.0.50.1 (x86_64-apple-darwin10.8.0, NS appkit-1038.36 Version 10.6.8 (Build 10K549)) of 2014-10-01 on MP.local Repository revision: 117996 dmantipov <at> yandex.ru-20141001132108-zdsxru2390mqyjlu Windowing system distributor `Apple', version 10.3.1038 Configured using: `configure --with-ns' Configured features: ACL LIBXML2 ZLIB Important settings: locale-coding-system: utf-8-unix Major mode: Fundamental Minor modes in effect: sd-mode: t sb-mode: t tb-mode: t shell-dirtrack-mode: t cm-mode: t frame-bufs-mode: t bc-mode: t ds-mode: t ml-mode: t Recent input: <escape> x r e p o r t - e m a c s - b u g <return > Recent messages: Wrote /Users/HOME/.0.data/.0.emacs/.lock Load-path shadows: /Users/HOME/.0.data/.0.emacs/.0.wl/md4 hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/md4 /Users/HOME/.0.data/.0.emacs/.0.wl/hex-util hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/hex-util /Users/HOME/.0.data/.0.emacs/.0.wl/sasl hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/net/sasl /Users/HOME/.0.data/.0.emacs/.0.wl/sasl-ntlm hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/net/sasl-ntlm /Users/HOME/.0.data/.0.emacs/.0.wl/sasl-digest hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/net/sasl-digest /Users/HOME/.0.data/.0.emacs/.0.wl/sasl-cram hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/net/sasl-cram /Users/HOME/.0.data/.0.emacs/.0.wl/ntlm hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/net/ntlm /Users/HOME/.0.data/.0.emacs/.0.wl/hmac-md5 hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/net/hmac-md5 /Users/HOME/.0.data/.0.emacs/.0.wl/hmac-def hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/net/hmac-def /Users/HOME/.0.data/.0.emacs/.0.wl/rfc2368 hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/mail/rfc2368 /Users/HOME/.0.data/.0.emacs/.0.wl/utf7 hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/gnus/utf7 /Users/HOME/.0.data/.0.emacs/.0.wl/smime hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/gnus/smime /Users/HOME/.0.data/.0.emacs/.0.wl/pgg hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/obsolete/pgg /Users/HOME/.0.data/.0.emacs/.0.wl/pgg-pgp5 hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/obsolete/pgg-pgp5 /Users/HOME/.0.data/.0.emacs/.0.wl/pgg-pgp hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/obsolete/pgg-pgp /Users/HOME/.0.data/.0.emacs/.0.wl/pgg-parse hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/obsolete/pgg-parse /Users/HOME/.0.data/.0.emacs/.0.wl/pgg-gpg hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/obsolete/pgg-gpg /Users/HOME/.0.data/.0.emacs/.0.wl/pgg-def hides /Users/HOME/.0.data/.0.emacs/Emacs_10_01_2014.app/Contents/Resources/lisp/obsolete/pgg-def Features: (shadow disp-table mime-setup mail-mime-setup semi-setup mime-image modb-standard elmo-imap4 emacsbug lawlist-desktop frameset lawlist-bk lawlist-arc lawlist-dv lawlist-mc rect lawlist-ztree lawlist-wl w3m-load mime-w3m w3m browse-url doc-view jka-compr image-mode w3m-hist w3m-fb bookmark-w3m w3m-ems mule-util w3m-ccl w3m-favicon w3m-image w3m-proc w3m-util wl-demo wl-spam elmo-spam elsp-header elsp-generic wl-fldmgr wl-score smtp sasl sasl-anonymous sasl-login sasl-plain wl-news wl-address pldap wl-thread wl-action wl-e21 wl-draft wl-template wl-summary ps-print ps-def lpr wl-refile wl-message wl-mime pgg mime-pgp mime-play filename mime-edit eword-encode pgg-parse pccl pccl-20 ccl pgg-def signature sendmail elmo-mime mmelmo-buffer mmelmo-imap mime-view mime-conf calist semi-def mmimap mime-parse mmbuffer wl-highlight elmo-filter elmo-multi elmo-nntp wl-folder wl wl-util crm pp elmo-pop3 elmo-net elmo-cache elmo-map elmo-dop elmo-flag elmo-localdir wl-vars elmo elmo-signal elmo-msgdb modb modb-generic modb-entity mime mmgeneric elmo-util emu invisible inv-23 poem poem-e20 poem-e20_3 utf7 eword-decode mel mime-def alist std11 mcharset mcs-20 mcs-e20 pces pces-e20 pces-20 broken pcustom elmo-date elmo-vars path-util poe pym static product wl-version elmo-version apel-ver luna lawlist-vr-hr lawlist-test lawlist-sb lawlist-vl lawlist-ln lawlist-hl lawlist-parens lawlist-dired tramp-sh lawlist-ws lawlist-calc lawlist-flyspell lawlist-yas lawlist-elisp lawlist-tex-mode skeleton compare-w lawlist-txt-mode lawlist-tabbar lawlist-github ido view vc-git vc vc-dispatcher tramp tramp-compat tramp-loaddefs trampver shell thingatpt time-stamp log-view log-edit message mml mml-sec mm-decode mm-bodies mm-encode gmm-utils mailheader pcvs-util add-log json help-mode grep compile find-lisp epa epg epg-config ediff-merg ediff-wind ediff-diff ediff-mult ediff-help ediff-init ediff-util ediff ert ewoc debug eieio-base diff-mode conf-mode autorevert filenotify lorg-calendar org-element lorg-search org-agenda context-menu dired-read-filename dired count-business-days lawlist-toodledo url-http tls url url-proxy url-privacy url-expand url-methods url-history mailcap url-auth url-cookie url-domsuf url-util url-parse auth-source eieio eieio-core password-cache url-gw url-vars lawlist-org lawlist-calendar org byte-opt bytecomp byte-compile cconv org-macro org-footnote org-pcomplete pcomplete org-list org-faces org-entities noutline outline org-version ob-emacs-lisp ob ob-tangle org-src ob-ref ob-lob ob-table ob-keys ob-exp ob-comint ob-core ob-eval org-compat org-macs org-loaddefs find-func cal-menu easymenu calendar cal-loaddefs format-spec lawlist-frame lawlist-cm lawlist-bbdb gnus gnus-ems nnheader gnus-util mail-utils wid-edit mail-parse rfc2231 rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mailabbrev mail-extr rfc822 cl timezone lawlist-grep lawlist-compile rx comint ansi-color ring lawlist-frame-bufs advice derived lawlist-window lawlist-print lawlist-undo pcase lawlist-tm lawlist-bc lawlist-as cl-macs gv lawlist-ds lawlist-ml easy-mmode lawlist-misc lawlist-keymap edmacro kmacro eldoc cl-loaddefs cl-lib help-fns savehist saveplace server time-date tooltip electric uniquify ediff-hook vc-hooks lisp-float-type mwheel ns-win tool-bar dnd fontset image regexp-opt fringe tabulated-list newcomment elisp-mode lisp-mode prog-mode register page menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock syntax facemenu font-core frame cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew greek romanian slovak czech european ethiopic indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer nadvice loaddefs button faces cus-face macroexp files text-properties overlay sha1 md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote make-network-process cocoa ns multi-tty emacs) Memory information: ((conses 16 1229677 95833) (symbols 48 61646 0) (miscs 40 105 150) (strings 32 132512 13095) (string-bytes 1 4616193) (vectors 16 33496) (vector-slots 8 697599 22896) (floats 8 942 252) (intervals 56 4202 0) (buffers 976 11))
GNU bug tracking system
Copyright (C) 1999 Darren O. Benham,
1997,2003 nCipher Corporation Ltd,
1994-97 Ian Jackson.