From 70468157b399e6e06902dc031b388a9ef31bf6b2 Mon Sep 17 00:00:00 2001 From: "Robert J. Chassell" Date: Tue, 31 Oct 2006 18:04:34 +0000 Subject: * eintr-2: updated `Introduction to Programming in Emacs Lisp' --- info/eintr-2 | 110 +++++++++++++++++++++++++---------------------------------- 1 file changed, 47 insertions(+), 63 deletions(-) (limited to 'info') diff --git a/info/eintr-2 b/info/eintr-2 index d48cfc3c7d1..2b96d6e0c42 100644 --- a/info/eintr-2 +++ b/info/eintr-2 @@ -10,7 +10,7 @@ END-INFO-DIR-ENTRY This is an `Introduction to Programming in Emacs Lisp', for people who are not programmers. -Edition 3.00, 2006 Oct 31 +Edition 3.01, 2006 Oct 31 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1997, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc. @@ -38,6 +38,46 @@ License". this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development." + +File: eintr, Node: See variable current value, Next: defvar and asterisk, Prev: defvar, Up: defvar + +Seeing the Current Value of a Variable +-------------------------------------- + +You can see the current value of a variable, any variable, by using the +`describe-variable' function, which is usually invoked by typing `C-h +v'. If you type `C-h v' and then `kill-ring' (followed by ) when +prompted, you will see what is in your current kill ring--this may be +quite a lot! Conversely, if you have been doing nothing this Emacs +session except read this document, you may have nothing in it. Also, +you will see the documentation for `kill-ring': + + Documentation: + List of killed text sequences. + Since the kill ring is supposed to interact nicely with cut-and-paste + facilities offered by window systems, use of this variable should + interact nicely with `interprogram-cut-function' and + `interprogram-paste-function'. The functions `kill-new', + `kill-append', and `current-kill' are supposed to implement this + interaction; you may want to use them instead of manipulating the kill + ring directly. + +The kill ring is defined by a `defvar' in the following way: + + (defvar kill-ring nil + "List of killed text sequences. + ...") + +In this variable definition, the variable is given an initial value of +`nil', which makes sense, since if you have saved nothing, you want +nothing back if you give a `yank' command. The documentation string is +written just like the documentation string of a `defun'. As with the +documentation string of the `defun', the first line of the +documentation should be a complete sentence, since some commands, like +`apropos', print only the first line of documentation. Succeeding +lines should not be indented; otherwise they look odd when you use `C-h +v' (`describe-variable'). +  File: eintr, Node: defvar and asterisk, Prev: See variable current value, Up: defvar @@ -6795,13 +6835,12 @@ characters, whitespace is added to fill out to this number. (Buffer names can and often should be longer than 12 characters; this length works well in a typical 80 column wide window.) -`:eval' was a new feature in GNU Emacs version 21. It says to evaluate -the following form and use the result as a string to display. In this -case, the expression displays the first component of the full system -name. The end of the first component is a `.' (`period'), so I use the -`string-match' function to tell me the length of the first component. -The substring from the zeroth character to that length is the name of -the machine. +`:eval' says to evaluate the following form and use the result as a +string to display. In this case, the expression displays the first +component of the full system name. The end of the first component is a +`.' (`period'), so I use the `string-match' function to tell me the +length of the first component. The substring from the zeroth character +to that length is the name of the machine. This is the expression: @@ -7445,58 +7484,3 @@ To return to the old value for the length of the kill ring, evaluate: * yank-pop:: * ring file:: - -File: eintr, Node: current-kill, Next: yank, Prev: Kill Ring, Up: Kill Ring - -B.1 The `current-kill' Function -=============================== - -The `current-kill' function changes the element in the kill ring to -which `kill-ring-yank-pointer' points. (Also, the `kill-new' function -sets `kill-ring-yank-pointer' to point to the latest element of the the -kill ring.) - -The `current-kill' function is used by `yank' and by `yank-pop'. Here -is the code for `current-kill': - - (defun current-kill (n &optional do-not-move) - "Rotate the yanking point by N places, and then return that kill. - If N is zero, `interprogram-paste-function' is set, and calling it - returns a string, then that string is added to the front of the - kill ring and returned as the latest kill. - If optional arg DO-NOT-MOVE is non-nil, then don't actually move the - yanking point; just return the Nth kill forward." - (let ((interprogram-paste (and (= n 0) - interprogram-paste-function - (funcall interprogram-paste-function)))) - (if interprogram-paste - (progn - ;; Disable the interprogram cut function when we add the new - ;; text to the kill ring, so Emacs doesn't try to own the - ;; selection, with identical text. - (let ((interprogram-cut-function nil)) - (kill-new interprogram-paste)) - interprogram-paste) - (or kill-ring (error "Kill ring is empty")) - (let ((ARGth-kill-element - (nthcdr (mod (- n (length kill-ring-yank-pointer)) - (length kill-ring)) - kill-ring))) - (or do-not-move - (setq kill-ring-yank-pointer ARGth-kill-element)) - (car ARGth-kill-element))))) - -In addition, the `kill-new' function sets `kill-ring-yank-pointer' to -the latest element of the the kill ring. And indirectly so does -`kill-append', since it calls `kill-new'. In addition, `kill-region' -and `kill-line' call the `kill-new' function. - -Here is the line in `kill-new', which is explained in *Note The -`kill-new' function: kill-new function. - - (setq kill-ring-yank-pointer kill-ring) - -* Menu: - -* Understanding current-kill:: - -- cgit v1.2.1