Enhancements to Snake.el

Enhancements to Snake.el

[Stuart Hacking]

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I have made the following small enhancements to snake.el:

- Some variables are now customizable
- By default, apples will spawn at random locations. (Although it is
possible to toggle the original behaviour.)
- Added some extra doc strings to keep Checkdoc happy.

Regards,

--Stuart

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--- C:\Dev\emacs-23.1\lisp\play\snake.el        2009-06-21 12:38:02.000000000 +0100
+++ C:\emacs-23.1\lisp\play\snake.el    2010-07-28 14:20:00.852191800 +0100
@@ -1,7 +1,7 @@
 ;;; snake.el --- implementation of Snake for Emacs

 ;; Copyright (C) 1997, 2001, 2002, 2003, 2004, 2005,
-;;   2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+;;   2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

 ;; Author: Glynn Clements <glynn@sensei.co.uk>
 ;; Created: 1997-09-10
@@ -32,6 +32,34 @@
 (require 'gamegrid)

 ;; ;;;;;;;;;;;;; customization variables ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+(defgroup snake nil
+  "Classic game of Snake (or Nibbles)."
+  :prefix "snake-"
+  :group 'games)
+
+(defcustom snake-buffer-name "*Snake*"
+  "Name used for Snake buffer."
+  :group 'snake :type 'string)
+
+(defcustom snake-initial-length 5
+  "Initial length of snake."
+  :group 'snake :type 'integer)
+
+(defcustom snake-spawn-rate 5
+  "Rate at which new apples will be desposited."
+  :group 'snake :type 'integer)
+
+(defcustom snake-score-file "snake-scores"
+  "File for holding high scores.
+It is not safe to put this in /tmp.
+Someone could make a symlink in /tmp
+pointing to a file you don't want to clobber."
+  :group 'snake :type 'file)
+
+(defcustom snake-randomize-apples t
+  "If non-nil, apples will be deposited at random.
+If nil, then apples will be dropped behind the snake."
+  :group 'snake :type 'boolean)

 (defvar snake-use-glyphs-flag t
   "Non-nil means use glyphs when available.")
@@ -39,9 +67,6 @@
 (defvar snake-use-color-flag t
   "Non-nil means use color when available.")

-(defvar snake-buffer-name "*Snake*"
-  "Name used for Snake buffer.")
-
 (defvar snake-buffer-width 30
   "Width of used portion of buffer.")

@@ -54,9 +79,6 @@
 (defvar snake-height 20
   "Height of playing area.")

-(defvar snake-initial-length 5
-  "Initial length of snake.")
-
 (defvar snake-initial-x 10
   "Initial X position of snake.")

@@ -81,12 +103,6 @@
 (defvar snake-score-y snake-height
   "Y position of score.")

-;; It is not safe to put this in /tmp.
-;; Someone could make a symlink in /tmp
-;; pointing to a file you don't want to clobber.
-(defvar snake-score-file "snake-scores"
-  "File for holding high scores.")
-
 ;; ;;;;;;;;;;;;; display options ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

 (defvar snake-blank-options
@@ -194,6 +210,7 @@
 ;; ;;;;;;;;;;;;;;;; game functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

 (defun snake-display-options ()
+  "Set snake buffer display options."
   (let ((options (make-vector 256 nil)))
     (loop for c from 0 to 255 do
       (aset options c
@@ -212,6 +229,7 @@
     options))

 (defun snake-update-score ()
+  "Update the score string."
   (let* ((string (format "Score:  %05d" snake-score))
         (len (length string)))
     (loop for x from 0 to (1- len) do
@@ -220,6 +238,7 @@
                         (aref string x)))))

 (defun snake-init-buffer ()
+  "Initialize snake buffer."
   (gamegrid-init-buffer snake-buffer-width
                        snake-buffer-height
                        snake-space)
@@ -232,6 +251,7 @@
                (gamegrid-set-cell x y snake-blank)))))

 (defun snake-reset-game ()
+  "Reset snake game."
   (gamegrid-kill-timer)
   (snake-init-buffer)
   (setq snake-length           snake-initial-length
@@ -276,10 +296,12 @@
                      (tail-pos (cadr last-cons))
                      (x0 (aref tail-pos 0))
                      (y0 (aref tail-pos 1)))
-                (gamegrid-set-cell x0 y0
-                                   (if (= (% snake-cycle 5) 0)
-                                       snake-dot
-                                     snake-blank))
+                 (gamegrid-set-cell x0 y0 snake-blank)
+                 (if (= (% snake-cycle snake-spawn-rate) 0)
+                     ; Maintain existing behaviour as customizable variable.
+                     (if snake-randomize-apples
+                         (snake-put-apple)
+                       (gamegrid-set-cell x0 y0 snake-dot)))
                 (incf snake-cycle)
                 (setcdr last-cons nil))))
        (gamegrid-set-cell x y snake-snake)
@@ -287,7 +309,15 @@
              (cons (vector x y) snake-positions))
          (setq snake-moved-p nil)))))

+(defun snake-put-apple ()
+  "Deposit an apple at a random location."
+  (let ((x (1+ (random (- snake-width 2))))
+        (y (1+ (random (- snake-height 2)))))
+    (if (= (gamegrid-get-cell x y) snake-blank)
+        (gamegrid-set-cell x y snake-dot))))
+
 (defun snake-update-velocity ()
+  "Update the snake's velocity."
   (unless snake-moved-p
     (if snake-velocity-queue
        (let ((new-vel (car (last snake-velocity-queue))))
@@ -350,6 +380,7 @@
   (message (and snake-paused "Game paused (press p to resume)")))

 (defun snake-active-p ()
+  "Is snake the active mode check."
   (eq (current-local-map) snake-mode-map))

 (put 'snake-mode 'mode-class 'special)
@@ -358,8 +389,7 @@
   "A mode for playing Snake.

 Snake mode keybindings:
-   \\{snake-mode-map}
-"
+   \\{snake-mode-map}"
   (kill-all-local-variables)

   (add-hook 'kill-buffer-hook 'gamegrid-kill-timer nil t)

Re: Enhancements to Snake.el

[Juanma Barranquero]

> I have made the following small enhancements to snake.el:
> - Some variables are now customizable
> - By default, apples will spawn at random locations. (Although it is
> possible to toggle the original behaviour.)
> - Added some extra doc strings to keep Checkdoc happy.

Looks OK, but I think the change is at the threshold were it is
(almost?) large enough that we would need for you to sign papers. Have
you done so?

Please resend the patch to bug-gnu-emacs@gnu.org, so it is not
forgotten. Try starting the message with

Package: emacs
Severity: wishlist
Tags: patch

followed by an empty line, to assign the bug to the relevant package,
etc. (I'm not sure the Tags: pseudoheader will work, but there's no
harm in trying).

Thanks,

    Juanma