This is Info file elisp, produced by Makeinfo version 1.68 from the input file elisp.texi. INFO-DIR-SECTION Editors START-INFO-DIR-ENTRY * Elisp: (elisp). The Emacs Lisp Reference Manual. END-INFO-DIR-ENTRY This version is the edition 2.5 of the GNU Emacs Lisp Reference Manual. It corresponds to Emacs Version 20.3 Published by the Free Software Foundation 59 Temple Place, Suite 330 Boston, MA 02111-1307 USA Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled "GNU General Public License" is included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the section entitled "GNU General Public License" may be included in a translation approved by the Free Software Foundation instead of in the original English.  File: elisp, Node: Blinking, Next: Inverse Video, Prev: Faces, Up: Display Blinking Parentheses ==================== This section describes the mechanism by which Emacs shows a matching open parenthesis when the user inserts a close parenthesis. - Variable: blink-paren-function The value of this variable should be a function (of no arguments) to be called whenever a character with close parenthesis syntax is inserted. The value of `blink-paren-function' may be `nil', in which case nothing is done. - User Option: blink-matching-paren If this variable is `nil', then `blink-matching-open' does nothing. - User Option: blink-matching-paren-distance This variable specifies the maximum distance to scan for a matching parenthesis before giving up. - User Option: blink-matching-delay This variable specifies the number of seconds for the cursor to remain at the matching parenthesis. A fraction of a second often gives good results, but the default is 1, which works on all systems. - Command: blink-matching-open This function is the default value of `blink-paren-function'. It assumes that point follows a character with close parenthesis syntax and moves the cursor momentarily to the matching opening character. If that character is not already on the screen, it displays the character's context in the echo area. To avoid long delays, this function does not search farther than `blink-matching-paren-distance' characters. Here is an example of calling this function explicitly. (defun interactive-blink-matching-open () "Indicate momentarily the start of sexp before point." (interactive) (let ((blink-matching-paren-distance (buffer-size)) (blink-matching-paren t)) (blink-matching-open)))  File: elisp, Node: Inverse Video, Next: Usual Display, Prev: Blinking, Up: Display Inverse Video ============= - User Option: inverse-video This variable controls whether Emacs uses inverse video for all text on the screen. Non-`nil' means yes, `nil' means no. The default is `nil'. - User Option: mode-line-inverse-video This variable controls the use of inverse video for mode lines. If it is non-`nil', then mode lines are displayed in inverse video. Otherwise, mode lines are displayed normally, just like text. The default is `t'. For window frames, this displays mode lines using the face named `modeline', which is normally the inverse of the default face unless you change it.  File: elisp, Node: Usual Display, Next: Display Tables, Prev: Inverse Video, Up: Display Usual Display Conventions ========================= The usual display conventions define how to display each character code. You can override these conventions by setting up a display table (*note Display Tables::.). Here are the usual display conventions: * Character codes 32 through 126 map to glyph codes 32 through 126. Normally this means they display as themselves. * Character code 9 is a horizontal tab. It displays as whitespace up to a position determined by `tab-width'. * Character code 10 is a newline. * All other codes in the range 0 through 31, and code 127, display in one of two ways according to the value of `ctl-arrow'. If it is non-`nil', these codes map to sequences of two glyphs, where the first glyph is the ASCII code for `^'. (A display table can specify a glyph to use instead of `^'.) Otherwise, these codes map just like the codes in the range 128 to 255. * Character codes 128 through 255 map to sequences of four glyphs, where the first glyph is the ASCII code for `\', and the others are digit characters representing the character code in octal. (A display table can specify a glyph to use instead of `\'.) * Multibyte character codes above 256 are displayed as themselves, or as a question mark or empty box if the terminal cannot display that character. The usual display conventions apply even when there is a display table, for any character whose entry in the active display table is `nil'. Thus, when you set up a display table, you need only specify the characters for which you want special behavior. These variables affect the way certain characters are displayed on the screen. Since they change the number of columns the characters occupy, they also affect the indentation functions. These variables also affect how the mode line is displayed; if you want to force redisplay of the mode line using the new values, call the function `force-mode-line-update' (*note Mode Line Format::.). - User Option: ctl-arrow This buffer-local variable controls how control characters are displayed. If it is non-`nil', they are displayed as a caret followed by the character: `^A'. If it is `nil', they are displayed as a backslash followed by three octal digits: `\001'. - Variable: default-ctl-arrow The value of this variable is the default value for `ctl-arrow' in buffers that do not override it. *Note Default Value::. - User Option: tab-width The value of this variable is the spacing between tab stops used for displaying tab characters in Emacs buffers. The default is 8. Note that this feature is completely independent of the user-settable tab stops used by the command `tab-to-tab-stop'. *Note Indent Tabs::.  File: elisp, Node: Display Tables, Next: Beeping, Prev: Usual Display, Up: Display Display Tables ============== You can use the "display table" feature to control how all possible character codes display on the screen. This is useful for displaying European languages that have letters not in the ASCII character set. The display table maps each character code into a sequence of "glyphs", each glyph being an image that takes up one character position on the screen. You can also define how to display each glyph on your terminal, using the "glyph table". Display tables affect how the mode line is displayed; if you want to force redisplay of the mode line using a new display table, call `force-mode-line-update' (*note Mode Line Format::.). * Menu: * Display Table Format:: What a display table consists of. * Active Display Table:: How Emacs selects a display table to use. * Glyphs:: How to define a glyph, and what glyphs mean.  File: elisp, Node: Display Table Format, Next: Active Display Table, Up: Display Tables Display Table Format -------------------- A display table is actually a char-table (*note Char-Tables::.) with `display-table' as its subtype. - Function: make-display-table This creates and returns a display table. The table initially has `nil' in all elements. The ordinary elements of the display table are indexed by character codes; the element at index C says how to display the character code C. The value should be `nil' or a vector of glyph values (*note Glyphs::.). If an element is `nil', it says to display that character according to the usual display conventions (*note Usual Display::.). If you use the display table to change the display of newline characters, the whole buffer will be displayed as one long "line." The display table also has six "extra slots" which serve special purposes. Here is a table of their meanings; `nil' in any slot means to use the default for that slot, as stated below. 0 The glyph for the end of a truncated screen line (the default for this is `$'). *Note Glyphs::. 1 The glyph for the end of a continued line (the default is `\'). 2 The glyph for indicating a character displayed as an octal character code (the default is `\'). 3 The glyph for indicating a control character (the default is `^'). 4 A vector of glyphs for indicating the presence of invisible lines (the default is `...'). *Note Selective Display::. 5 The glyph used to draw the border between side-by-side windows (the default is `|'). *Note Splitting Windows::. For example, here is how to construct a display table that mimics the effect of setting `ctl-arrow' to a non-`nil' value: (setq disptab (make-display-table)) (let ((i 0)) (while (< i 32) (or (= i ?\t) (= i ?\n) (aset disptab i (vector ?^ (+ i 64)))) (setq i (1+ i))) (aset disptab 127 (vector ?^ ??))) - Function: display-table-slot DISPLAY-TABLE SLOT This function returns the value of the extra slot SLOT of DISPLAY-TABLE. The argument SLOT may be a number from 0 to 5 inclusive, or a slot name (symbol). Valid symbols are `truncation', `wrap', `escape', `control', `selective-display', and `vertical-border'. - Function: set-display-table-slot DISPLAY-TABLE SLOT VALUE This function stores VALUE in the extra slot SLOT of DISPLAY-TABLE. The argument SLOT may be a number from 0 to 5 inclusive, or a slot name (symbol). Valid symbols are `truncation', `wrap', `escape', `control', `selective-display', and `vertical-border'.  File: elisp, Node: Active Display Table, Next: Glyphs, Prev: Display Table Format, Up: Display Tables Active Display Table -------------------- Each window can specify a display table, and so can each buffer. When a buffer B is displayed in window W, display uses the display table for window W if it has one; otherwise, the display table for buffer B if it has one; otherwise, the standard display table if any. The display table chosen is called the "active" display table. - Function: window-display-table WINDOW This function returns WINDOW's display table, or `nil' if WINDOW does not have an assigned display table. - Function: set-window-display-table WINDOW TABLE This function sets the display table of WINDOW to TABLE. The argument TABLE should be either a display table or `nil'. - Variable: buffer-display-table This variable is automatically buffer-local in all buffers; its value in a particular buffer specifies the display table for that buffer. If it is `nil', that means the buffer does not have an assigned display table. - Variable: standard-display-table This variable's value is the default display table, used whenever a window has no display table and neither does the buffer displayed in that window. This variable is `nil' by default. If there is no display table to use for a particular window--that is, if the window specifies none, its buffer specifies none, and `standard-display-table' is `nil'--then Emacs uses the usual display conventions for all character codes in that window. *Note Usual Display::.  File: elisp, Node: Glyphs, Prev: Active Display Table, Up: Display Tables Glyphs ------ A "glyph" is a generalization of a character; it stands for an image that takes up a single character position on the screen. Glyphs are represented in Lisp as integers, just as characters are. The meaning of each integer, as a glyph, is defined by the glyph table, which is the value of the variable `glyph-table'. - Variable: glyph-table The value of this variable is the current glyph table. It should be a vector; the Gth element defines glyph code G. If the value is `nil' instead of a vector, then all glyphs are simple (see below). Here are the possible types of elements in the glyph table: STRING Send the characters in STRING to the terminal to output this glyph. This alternative is available on character terminals, but not under a window system. INTEGER Define this glyph code as an alias for glyph code INTEGER. You can use an alias to specify a face code for the glyph; see below. `nil' This glyph is simple. On an ordinary terminal, the glyph code mod 524288 is the character to output. In a window system, the glyph code mod 524288 is the character to output, and the glyph code divided by 524288 specifies the face number (*note Face Functions::.) to use while outputting it. (524288 is 2**19.) *Note Faces::. If a glyph code is greater than or equal to the length of the glyph table, that code is automatically simple.  File: elisp, Node: Beeping, Next: Window Systems, Prev: Display Tables, Up: Display Beeping ======= This section describes how to make Emacs ring the bell (or blink the screen) to attract the user's attention. Be conservative about how often you do this; frequent bells can become irritating. Also be careful not to use just beeping when signaling an error is more appropriate. (*Note Errors::.) - Function: ding &optional DO-NOT-TERMINATE This function beeps, or flashes the screen (see `visible-bell' below). It also terminates any keyboard macro currently executing unless DO-NOT-TERMINATE is non-`nil'. - Function: beep &optional DO-NOT-TERMINATE This is a synonym for `ding'. - User Option: visible-bell This variable determines whether Emacs should flash the screen to represent a bell. Non-`nil' means yes, `nil' means no. This is effective on a window system, and on a character-only terminal provided the terminal's Termcap entry defines the visible bell capability (`vb'). - Variable: ring-bell-function If this is non-`nil', it specifies how Emacs should "ring the bell." Its value should be a function of no arguments.  File: elisp, Node: Window Systems, Prev: Beeping, Up: Display Window Systems ============== Emacs works with several window systems, most notably the X Window System. Both Emacs and X use the term "window", but use it differently. An Emacs frame is a single window as far as X is concerned; the individual Emacs windows are not known to X at all. - Variable: window-system This variable tells Lisp programs what window system Emacs is running under. The possible values are `x' Emacs is displaying using X. `pc' Emacs is displaying using MSDOS. `w32' Emacs is displaying using Windows NT or Windows 95. `nil' Emacs is using a character-based terminal. - Variable: window-setup-hook This variable is a normal hook which Emacs runs after handling the initialization files. Emacs runs this hook after it has completed loading your `.emacs' file, the default initialization file (if any), and the terminal-specific Lisp code, and running the hook `term-setup-hook'. This hook is used for internal purposes: setting up communication with the window system, and creating the initial window. Users should not interfere with it.  File: elisp, Node: Calendar, Next: System Interface, Prev: Display, Up: Top Customizing the Calendar and Diary ********************************** There are many customizations that you can use to make the calendar and diary suit your personal tastes. * Menu: * Calendar Customizing:: Defaults you can set. * Holiday Customizing:: Defining your own holidays. * Date Display Format:: Changing the format. * Time Display Format:: Changing the format. * Daylight Savings:: Changing the default. * Diary Customizing:: Defaults you can set. * Hebrew/Islamic Entries:: How to obtain them. * Fancy Diary Display:: Enhancing the diary display, sorting entries, using included diary files. * Sexp Diary Entries:: Fancy things you can do. * Appt Customizing:: Customizing appointment reminders.  File: elisp, Node: Calendar Customizing, Next: Holiday Customizing, Up: Calendar Customizing the Calendar ======================== If you set the variable `view-diary-entries-initially' to `t', calling up the calendar automatically displays the diary entries for the current date as well. The diary dates appear only if the current date is visible. If you add both of the following lines to your `.emacs' file: (setq view-diary-entries-initially t) (calendar) this displays both the calendar and diary windows whenever you start Emacs. Similarly, if you set the variable `view-calendar-holidays-initially' to `t', entering the calendar automatically displays a list of holidays for the current three-month period. The holiday list appears in a separate window. You can set the variable `mark-diary-entries-in-calendar' to `t' in order to mark any dates with diary entries. This takes effect whenever the calendar window contents are recomputed. There are two ways of marking these dates: by changing the face (*note Faces::.), if the display supports that, or by placing a plus sign (`+') beside the date otherwise. Similarly, setting the variable `mark-holidays-in-calendar' to `t' marks holiday dates, either with a change of face or with an asterisk (`*'). The variable `calendar-holiday-marker' specifies how to mark a date as being a holiday. Its value may be a character to insert next to the date, or a face name to use for displaying the date. Likewise, the variable `diary-entry-marker' specifies how to mark a date that has diary entries. The calendar creates faces named `holiday-face' and `diary-face' for these purposes; those symbols are the default values of these variables, when Emacs supports multiple faces on your terminal. The variable `calendar-load-hook' is a normal hook run when the calendar package is first loaded (before actually starting to display the calendar). Starting the calendar runs the normal hook `initial-calendar-window-hook'. Recomputation of the calendar display does not run this hook. But if you leave the calendar with the `q' command and reenter it, the hook runs again. The variable `today-visible-calendar-hook' is a normal hook run after the calendar buffer has been prepared with the calendar when the current date is visible in the window. One use of this hook is to replace today's date with asterisks; to do that, use the hook function `calendar-star-date'. (add-hook 'today-visible-calendar-hook 'calendar-star-date) Another standard hook function marks the current date, either by changing its face or by adding an asterisk. Here's how to use it: (add-hook 'today-visible-calendar-hook 'calendar-mark-today) The variable `calendar-today-marker' specifies how to mark today's date. Its value should be a character to insert next to the date or a face name to use for displaying the date. A face named `calendar-today-face' is provided for this purpose; that symbol is the default for this variable when Emacs supports multiple faces on your terminal. A similar normal hook, `today-invisible-calendar-hook' is run if the current date is *not* visible in the window.  File: elisp, Node: Holiday Customizing, Next: Date Display Format, Prev: Calendar Customizing, Up: Calendar Customizing the Holidays ======================== Emacs knows about holidays defined by entries on one of several lists. You can customize these lists of holidays to your own needs, adding or deleting holidays. The lists of holidays that Emacs uses are for general holidays (`general-holidays'), local holidays (`local-holidays'), Christian holidays (`christian-holidays'), Hebrew (Jewish) holidays (`hebrew-holidays'), Islamic (Moslem) holidays (`islamic-holidays'), and other holidays (`other-holidays'). The general holidays are, by default, holidays common throughout the United States. To eliminate these holidays, set `general-holidays' to `nil'. There are no default local holidays (but sites may supply some). You can set the variable `local-holidays' to any list of holidays, as described below. By default, Emacs does not include all the holidays of the religions that it knows, only those commonly found in secular calendars. For a more extensive collection of religious holidays, you can set any (or all) of the variables `all-christian-calendar-holidays', `all-hebrew-calendar-holidays', or `all-islamic-calendar-holidays' to `t'. If you want to eliminate the religious holidays, set any or all of the corresponding variables `christian-holidays', `hebrew-holidays', and `islamic-holidays' to `nil'. You can set the variable `other-holidays' to any list of holidays. This list, normally empty, is intended for individual use. Each of the lists (`general-holidays', `local-holidays', `christian-holidays', `hebrew-holidays', `islamic-holidays', and `other-holidays') is a list of "holiday forms", each holiday form describing a holiday (or sometimes a list of holidays). Here is a table of the possible kinds of holiday form. Day numbers and month numbers count starting from 1, but "dayname" numbers count Sunday as 0. The element STRING is always the name of the holiday, as a string. `(holiday-fixed MONTH DAY STRING)' A fixed date on the Gregorian calendar. `(holiday-float MONTH DAYNAME K STRING)' The Kth DAYNAME in MONTH on the Gregorian calendar (DAYNAME=0 for Sunday, and so on); negative K means count back from the end of the month. `(holiday-hebrew MONTH DAY STRING)' A fixed date on the Hebrew calendar. `(holiday-islamic MONTH DAY STRING)' A fixed date on the Islamic calendar. `(holiday-julian MONTH DAY STRING)' A fixed date on the Julian calendar. `(holiday-sexp SEXP STRING)' A date calculated by the Lisp expression SEXP. The expression should use the variable `year' to compute and return the date of a holiday, or `nil' if the holiday doesn't happen this year. The value of SEXP must represent the date as a list of the form `(MONTH DAY YEAR)'. `(if CONDITION HOLIDAY-FORM)' A holiday that happens only if CONDITION is true. `(FUNCTION [ARGS])' A list of dates calculated by the function FUNCTION, called with arguments ARGS. For example, suppose you want to add Bastille Day, celebrated in France on July 14. You can do this as follows: (setq other-holidays '((holiday-fixed 7 14 "Bastille Day"))) The holiday form `(holiday-fixed 7 14 "Bastille Day")' specifies the fourteenth day of the seventh month (July). Many holidays occur on a specific day of the week, at a specific time of month. Here is a holiday form describing Hurricane Supplication Day, celebrated in the Virgin Islands on the fourth Monday in August: (holiday-float 8 1 4 "Hurricane Supplication Day") Here the 8 specifies August, the 1 specifies Monday (Sunday is 0, Tuesday is 2, and so on), and the 4 specifies the fourth occurrence in the month (1 specifies the first occurrence, 2 the second occurrence, -1 the last occurrence, -2 the second-to-last occurrence, and so on). You can specify holidays that occur on fixed days of the Hebrew, Islamic, and Julian calendars too. For example, (setq other-holidays '((holiday-hebrew 10 2 "Last day of Hanukkah") (holiday-islamic 3 12 "Mohammed's Birthday") (holiday-julian 4 2 "Jefferson's Birthday"))) adds the last day of Hanukkah (since the Hebrew months are numbered with 1 starting from Nisan), the Islamic feast celebrating Mohammed's birthday (since the Islamic months are numbered from 1 starting with Muharram), and Thomas Jefferson's birthday, which is 2 April 1743 on the Julian calendar. To include a holiday conditionally, use either Emacs Lisp's `if' or the `holiday-sexp' form. For example, American presidential elections occur on the first Tuesday after the first Monday in November of years divisible by 4: (holiday-sexp (if (= 0 (% year 4)) (calendar-gregorian-from-absolute (1+ (calendar-dayname-on-or-before 1 (+ 6 (calendar-absolute-from-gregorian (list 11 1 year)))))) "US Presidential Election")) or (if (= 0 (% displayed-year 4)) (fixed 11 (extract-calendar-day (calendar-gregorian-from-absolute (1+ (calendar-dayname-on-or-before 1 (+ 6 (calendar-absolute-from-gregorian (list 11 1 displayed-year))))))) "US Presidential Election")) Some holidays just don't fit into any of these forms because special calculations are involved in their determination. In such cases you must write a Lisp function to do the calculation. To include eclipses, for example, add `(eclipses)' to `other-holidays' and write an Emacs Lisp function `eclipses' that returns a (possibly empty) list of the relevant Gregorian dates among the range visible in the calendar window, with descriptive strings, like this: (((6 27 1991) "Lunar Eclipse") ((7 11 1991) "Solar Eclipse") ... )  File: elisp, Node: Date Display Format, Next: Time Display Format, Prev: Holiday Customizing, Up: Calendar Date Display Format =================== You can customize the manner of displaying dates in the diary, in mode lines, and in messages by setting `calendar-date-display-form'. This variable holds a list of expressions that can involve the variables `month', `day', and `year', which are all numbers in string form, and `monthname' and `dayname', which are both alphabetic strings. In the American style, the default value of this list is as follows: ((if dayname (concat dayname ", ")) monthname " " day ", " year) while in the European style this value is the default: ((if dayname (concat dayname ", ")) day " " monthname " " year) The ISO standard date representation is this: (year "-" month "-" day) This specifies a typical American format: (month "/" day "/" (substring year -2))  File: elisp, Node: Time Display Format, Next: Daylight Savings, Prev: Date Display Format, Up: Calendar Time Display Format =================== The calendar and diary by default display times of day in the conventional American style with the hours from 1 through 12, minutes, and either `am' or `pm'. If you prefer the European style, also known in the US as military, in which the hours go from 00 to 23, you can alter the variable `calendar-time-display-form'. This variable is a list of expressions that can involve the variables `12-hours', `24-hours', and `minutes', which are all numbers in string form, and `am-pm' and `time-zone', which are both alphabetic strings. The default value of `calendar-time-display-form' is as follows: (12-hours ":" minutes am-pm (if time-zone " (") time-zone (if time-zone ")")) Here is a value that provides European style times: (24-hours ":" minutes (if time-zone " (") time-zone (if time-zone ")"))  File: elisp, Node: Daylight Savings, Next: Diary Customizing, Prev: Time Display Format, Up: Calendar Daylight Savings Time ===================== Emacs understands the difference between standard time and daylight savings time--the times given for sunrise, sunset, solstices, equinoxes, and the phases of the moon take that into account. The rules for daylight savings time vary from place to place and have also varied historically from year to year. To do the job properly, Emacs needs to know which rules to use. Some operating systems keep track of the rules that apply to the place where you are; on these systems, Emacs gets the information it needs from the system automatically. If some or all of this information is missing, Emacs fills in the gaps with the rules currently used in Cambridge, Massachusetts, which is the center of GNU's world. If the default choice of rules is not appropriate for your location, you can tell Emacs the rules to use by setting the variables `calendar-daylight-savings-starts' and `calendar-daylight-savings-ends'. Their values should be Lisp expressions that refer to the variable `year', and evaluate to the Gregorian date on which daylight savings time starts or (respectively) ends, in the form of a list `(MONTH DAY YEAR)'. The values should be `nil' if your area does not use daylight savings time. Emacs uses these expressions to determine the start and end dates of daylight savings time as holidays and for correcting times of day in the solar and lunar calculations. The values for Cambridge, Massachusetts are as follows: (calendar-nth-named-day 1 0 4 year) (calendar-nth-named-day -1 0 10 year) i.e., the first 0th day (Sunday) of the fourth month (April) in the year specified by `year', and the last Sunday of the tenth month (October) of that year. If daylight savings time were changed to start on October 1, you would set `calendar-daylight-savings-starts' to this: (list 10 1 year) For a more complex example, suppose daylight savings time begins on the first of Nisan on the Hebrew calendar. You should set `calendar-daylight-savings-starts' to this value: (calendar-gregorian-from-absolute (calendar-absolute-from-hebrew (list 1 1 (+ year 3760)))) because Nisan is the first month in the Hebrew calendar and the Hebrew year differs from the Gregorian year by 3760 at Nisan. If there is no daylight savings time at your location, or if you want all times in standard time, set `calendar-daylight-savings-starts' and `calendar-daylight-savings-ends' to `nil'. The variable `calendar-daylight-time-offset' specifies the difference between daylight savings time and standard time, measured in minutes. The value for Cambridge is 60. The variable `calendar-daylight-savings-starts-time' and the variable `calendar-daylight-savings-ends-time' specify the number of minutes after midnight local time when the transition to and from daylight savings time should occur. For Cambridge, both variables' values are 120.  File: elisp, Node: Diary Customizing, Next: Hebrew/Islamic Entries, Prev: Daylight Savings, Up: Calendar Customizing the Diary ===================== Ordinarily, the mode line of the diary buffer window indicates any holidays that fall on the date of the diary entries. The process of checking for holidays can take several seconds, so including holiday information delays the display of the diary buffer noticeably. If you'd prefer to have a faster display of the diary buffer but without the holiday information, set the variable `holidays-in-diary-buffer' to `nil'. The variable `number-of-diary-entries' controls the number of days of diary entries to be displayed at one time. It affects the initial display when `view-diary-entries-initially' is `t', as well as the command `M-x diary'. For example, the default value is 1, which says to display only the current day's diary entries. If the value is 2, both the current day's and the next day's entries are displayed. The value can also be a vector of seven elements: for example, if the value is `[0 2 2 2 2 4 1]' then no diary entries appear on Sunday, the current date's and the next day's diary entries appear Monday through Thursday, Friday through Monday's entries appear on Friday, while on Saturday only that day's entries appear. The variable `print-diary-entries-hook' is a normal hook run after preparation of a temporary buffer containing just the diary entries currently visible in the diary buffer. (The other, irrelevant diary entries are really absent from the temporary buffer; in the diary buffer, they are merely hidden.) The default value of this hook does the printing with the command `lpr-buffer'. If you want to use a different command to do the printing, just change the value of this hook. Other uses might include, for example, rearranging the lines into order by day and time. You can customize the form of dates in your diary file, if neither the standard American nor European styles suits your needs, by setting the variable `diary-date-forms'. This variable is a list of patterns for recognizing a date. Each date pattern is a list whose elements may be regular expressions (*note Regular Expressions::.) or the symbols `month', `day', `year', `monthname', and `dayname'. All these elements serve as patterns that match certain kinds of text in the diary file. In order for the date pattern, as a whole, to match, all of its elements must match consecutively. A regular expression in a date pattern matches in its usual fashion, using the standard syntax table altered so that `*' is a word constituent. The symbols `month', `day', `year', `monthname', and `dayname' match the month number, day number, year number, month name, and day name of the date being considered. The symbols that match numbers allow leading zeros; those that match names allow three-letter abbreviations and capitalization. All the symbols can match `*'; since `*' in a diary entry means "any day", "any month", and so on, it should match regardless of the date being considered. The default value of `diary-date-forms' in the American style is this: ((month "/" day "[^/0-9]") (month "/" day "/" year "[^0-9]") (monthname " *" day "[^,0-9]") (monthname " *" day ", *" year "[^0-9]") (dayname "\\W")) The date patterns in the list must be *mutually exclusive* and must not match any portion of the diary entry itself, just the date and one character of whitespace. If, to be mutually exclusive, the pattern must match a portion of the diary entry text--beyond the whitespace that ends the date--then the first element of the date pattern *must* be `backup'. This causes the date recognizer to back up to the beginning of the current word of the diary entry, after finishing the match. Even if you use `backup', the date pattern must absolutely not match more than a portion of the first word of the diary entry. The default value of `diary-date-forms' in the European style is this list: ((day "/" month "[^/0-9]") (day "/" month "/" year "[^0-9]") (backup day " *" monthname "\\W+\\<[^*0-9]") (day " *" monthname " *" year "[^0-9]") (dayname "\\W")) Notice the use of `backup' in the third pattern, because it needs to match part of a word beyond the date itself to distinguish it from the fourth pattern.  File: elisp, Node: Hebrew/Islamic Entries, Next: Fancy Diary Display, Prev: Diary Customizing, Up: Calendar Hebrew- and Islamic-Date Diary Entries ====================================== Your diary file can have entries based on Hebrew or Islamic dates, as well as entries based on the world-standard Gregorian calendar. However, because recognition of such entries is time-consuming and most people don't use them, you must explicitly enable their use. If you want the diary to recognize Hebrew-date diary entries, for example, you must do this: (add-hook 'nongregorian-diary-listing-hook 'list-hebrew-diary-entries) (add-hook 'nongregorian-diary-marking-hook 'mark-hebrew-diary-entries) If you want Islamic-date entries, do this: (add-hook 'nongregorian-diary-listing-hook 'list-islamic-diary-entries) (add-hook 'nongregorian-diary-marking-hook 'mark-islamic-diary-entries) Hebrew- and Islamic-date diary entries have the same formats as Gregorian-date diary entries, except that `H' precedes a Hebrew date and `I' precedes an Islamic date. Moreover, because the Hebrew and Islamic month names are not uniquely specified by the first three letters, you may not abbreviate them. For example, a diary entry for the Hebrew date Heshvan 25 could look like this: HHeshvan 25 Happy Hebrew birthday! and would appear in the diary for any date that corresponds to Heshvan 25 on the Hebrew calendar. And here is an Islamic-date diary entry that matches Dhu al-Qada 25: IDhu al-Qada 25 Happy Islamic birthday! As with Gregorian-date diary entries, Hebrew- and Islamic-date entries are nonmarking if they are preceded with an ampersand (`&'). Here is a table of commands used in the calendar to create diary entries that match the selected date and other dates that are similar in the Hebrew or Islamic calendar: `i h d' Add a diary entry for the Hebrew date corresponding to the selected date (`insert-hebrew-diary-entry'). `i h m' Add a diary entry for the day of the Hebrew month corresponding to the selected date (`insert-monthly-hebrew-diary-entry'). This diary entry matches any date that has the same Hebrew day-within-month as the selected date. `i h y' Add a diary entry for the day of the Hebrew year corresponding to the selected date (`insert-yearly-hebrew-diary-entry'). This diary entry matches any date which has the same Hebrew month and day-within-month as the selected date. `i i d' Add a diary entry for the Islamic date corresponding to the selected date (`insert-islamic-diary-entry'). `i i m' Add a diary entry for the day of the Islamic month corresponding to the selected date (`insert-monthly-islamic-diary-entry'). `i i y' Add a diary entry for the day of the Islamic year corresponding to the selected date (`insert-yearly-islamic-diary-entry'). These commands work much like the corresponding commands for ordinary diary entries: they apply to the date that point is on in the calendar window, and what they do is insert just the date portion of a diary entry at the end of your diary file. You must then insert the rest of the diary entry.  File: elisp, Node: Fancy Diary Display, Next: Sexp Diary Entries, Prev: Hebrew/Islamic Entries, Up: Calendar Fancy Diary Display =================== Diary display works by preparing the diary buffer and then running the hook `diary-display-hook'. The default value of this hook (`simple-diary-display') hides the irrelevant diary entries and then displays the buffer. However, if you specify the hook as follows, (add-hook 'diary-display-hook 'fancy-diary-display) this enables fancy diary display. It displays diary entries and holidays by copying them into a special buffer that exists only for the sake of display. Copying to a separate buffer provides an opportunity to change the displayed text to make it prettier--for example, to sort the entries by the dates they apply to. As with simple diary display, you can print a hard copy of the buffer with `print-diary-entries'. To print a hard copy of a day-by-day diary for a week by positioning point on Sunday of that week, type `7 d' and then do `M-x print-diary-entries'. As usual, the inclusion of the holidays slows down the display slightly; you can speed things up by setting the variable `holidays-in-diary-buffer' to `nil'. Ordinarily, the fancy diary buffer does not show days for which there are no diary entries, even if that day is a holiday. If you want such days to be shown in the fancy diary buffer, set the variable `diary-list-include-blanks' to `t'. If you use the fancy diary display, you can use the normal hook `list-diary-entries-hook' to sort each day's diary entries by their time of day. Here's how: (add-hook 'list-diary-entries-hook 'sort-diary-entries t) For each day, this sorts diary entries that begin with a recognizable time of day according to their times. Diary entries without times come first within each day. Fancy diary display also has the ability to process included diary files. This permits a group of people to share a diary file for events that apply to all of them. Lines in the diary file of this form: #include "FILENAME" includes the diary entries from the file FILENAME in the fancy diary buffer. The include mechanism is recursive, so that included files can include other files, and so on; you must be careful not to have a cycle of inclusions, of course. Here is how to enable the include facility: (add-hook 'list-diary-entries-hook 'include-other-diary-files) (add-hook 'mark-diary-entries-hook 'mark-included-diary-files) The include mechanism works only with the fancy diary display, because ordinary diary display shows the entries directly from your diary file.  File: elisp, Node: Sexp Diary Entries, Next: Appt Customizing, Prev: Fancy Diary Display, Up: Calendar Sexp Entries and the Fancy Diary Display ======================================== Sexp diary entries allow you to do more than just have complicated conditions under which a diary entry applies. If you use the fancy diary display, sexp entries can generate the text of the entry depending on the date itself. For example, an anniversary diary entry can insert the number of years since the anniversary date into the text of the diary entry. Thus the `%d' in this dairy entry: %%(diary-anniversary 10 31 1948) Arthur's birthday (%d years old) gets replaced by the age, so on October 31, 1990 the entry appears in the fancy diary buffer like this: Arthur's birthday (42 years old) If the diary file instead contains this entry: %%(diary-anniversary 10 31 1948) Arthur's %d%s birthday the entry in the fancy diary buffer for October 31, 1990 appears like this: Arthur's 42nd birthday Similarly, cyclic diary entries can interpolate the number of repetitions that have occurred: %%(diary-cyclic 50 1 1 1990) Renew medication (%d%s time) looks like this: Renew medication (5th time) in the fancy diary display on September 8, 1990. There is an early reminder diary sexp that includes its entry in the diary not only on the date of occurrence, but also on earlier dates. For example, if you want a reminder a week before your anniversary, you can use %%(diary-remind '(diary-anniversary 12 22 1968) 7) Ed's anniversary and the fancy diary will show Ruth & Ed's anniversary both on December 15 and on December 22. The function `diary-date' applies to dates described by a month, day, year combination, each of which can be an integer, a list of integers, or `t'. The value `t' means all values. For example, %%(diary-date '(10 11 12) 22 t) Rake leaves causes the fancy diary to show Rake leaves on October 22, November 22, and December 22 of every year. The function `diary-float' allows you to describe diary entries that apply to dates like the third Friday of November, or the last Tuesday in April. The parameters are the MONTH, DAYNAME, and an index N. The entry appears on the Nth DAYNAME of MONTH, where DAYNAME=0 means Sunday, 1 means Monday, and so on. If N is negative it counts backward from the end of MONTH. The value of MONTH can be a list of months, a single month, or `t' to specify all months. You can also use an optional parameter DAY to specify the Nth DAYNAME of MONTH on or after/before DAY; the value of DAY defaults to 1 if N is positive and to the last day of MONTH if N is negative. For example, %%(diary-float t 1 -1) Pay rent causes the fancy diary to show Pay rent on the last Monday of every month. The generality of sexp diary entries lets you specify any diary entry that you can describe algorithmically. A sexp diary entry contains an expression that computes whether the entry applies to any given date. If its value is non-`nil', the entry applies to that date; otherwise, it does not. The expression can use the variable `date' to find the date being considered; its value is a list (MONTH DAY YEAR) that refers to the Gregorian calendar. Suppose you get paid on the 21st of the month if it is a weekday, and on the Friday before if the 21st is on a weekend. Here is how to write a sexp diary entry that matches those dates: &%%(let ((dayname (calendar-day-of-week date)) (day (car (cdr date)))) (or (and (= day 21) (memq dayname '(1 2 3 4 5))) (and (memq day '(19 20)) (= dayname 5))) ) Pay check deposited The following sexp diary entries take advantage of the ability (in the fancy diary display) to concoct diary entries whose text varies based on the date: `%%(diary-sunrise-sunset)' Make a diary entry for the local times of today's sunrise and sunset. `%%(diary-phases-of-moon)' Make a diary entry for the phases (quarters) of the moon. `%%(diary-day-of-year)' Make a diary entry with today's day number in the current year and the number of days remaining in the current year. `%%(diary-iso-date)' Make a diary entry with today's equivalent ISO commercial date. `%%(diary-julian-date)' Make a diary entry with today's equivalent date on the Julian calendar. `%%(diary-astro-day-number)' Make a diary entry with today's equivalent astronomical (Julian) day number. `%%(diary-hebrew-date)' Make a diary entry with today's equivalent date on the Hebrew calendar. `%%(diary-islamic-date)' Make a diary entry with today's equivalent date on the Islamic calendar. `%%(diary-french-date)' Make a diary entry with today's equivalent date on the French Revolutionary calendar. `%%(diary-mayan-date)' Make a diary entry with today's equivalent date on the Mayan calendar. Thus including the diary entry &%%(diary-hebrew-date) causes every day's diary display to contain the equivalent date on the Hebrew calendar, if you are using the fancy diary display. (With simple diary display, the line `&%%(diary-hebrew-date)' appears in the diary for any date, but does nothing particularly useful.) These functions can be used to construct sexp diary entries based on the Hebrew calendar in certain standard ways: `%%(diary-rosh-hodesh)' Make a diary entry that tells the occurrence and ritual announcement of each new Hebrew month. `%%(diary-parasha)' Make a Saturday diary entry that tells the weekly synagogue scripture reading. `%%(diary-sabbath-candles)' Make a Friday diary entry that tells the *local time* of Sabbath candle lighting. `%%(diary-omer)' Make a diary entry that gives the omer count, when appropriate. `%%(diary-yahrzeit MONTH DAY YEAR) NAME' Make a diary entry marking the anniversary of a date of death. The date is the *Gregorian* (civil) date of death. The diary entry appears on the proper Hebrew calendar anniversary and on the day before. (In the European style, the order of the parameters is changed to DAY, MONTH, YEAR.)  File: elisp, Node: Appt Customizing, Prev: Sexp Diary Entries, Up: Calendar Customizing Appointment Reminders ================================= You can specify exactly how Emacs reminds you of an appointment, and how far in advance it begins doing so, by setting these variables: `appt-message-warning-time' The time in minutes before an appointment that the reminder begins. The default is 10 minutes. `appt-audible' If this is non-`nil', Emacs rings the terminal bell for appointment reminders. The default is `t'. `appt-visible' If this is non-`nil', Emacs displays the appointment message in the echo area. The default is `t'. `appt-display-mode-line' If this is non-`nil', Emacs displays the number of minutes to the appointment on the mode line. The default is `t'. `appt-msg-window' If this is non-`nil', Emacs displays the appointment message in another window. The default is `t'. `appt-disp-window-function' This variable holds a function to use to create the other window for the appointment message. `appt-delete-window-function' This variable holds a function to use to get rid of the appointment message window, when its time is up. `appt-display-duration' The number of seconds to display an appointment message. The default is 5 seconds.  File: elisp, Node: Tips, Next: GNU Emacs Internals, Prev: System Interface, Up: Top Tips and Conventions ******************** This chapter describes no additional features of Emacs Lisp. Instead it gives advice on making effective use of the features described in the previous chapters, and describes conventions Emacs Lisp programmers should follow. * Menu: * Coding Conventions:: Conventions for clean and robust programs. * Compilation Tips:: Making compiled code run fast. * Documentation Tips:: Writing readable documentation strings. * Comment Tips:: Conventions for writing comments. * Library Headers:: Standard headers for library packages.