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This file documents version 2.9 of logo.el.
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Logo.el is written for GNU Emacs 20.5 or newer, running under X11.
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You will (of-course) need Berkeley Logo (*v5.1* or newer) installed on
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It is *not* designed to be used with Xemacs, Gnu Emacs compiled
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without X support or Gnu Emacs started with -nw option. The last two
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will partly work, but I did not test it that way.
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Installing the Berkeley Logo package installs Logo-mode also. See the
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README file in the main ucblogo directory.
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EACH USER who wants to use Logo-mode must run the shell command
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------------------------------------------------
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Description of options for fine-tuning:
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Set this to change the size of the frame (window) for
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Logo-inferior-process buffer. If these forms are not present, the size
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is set to 80x24. (This will work properly only with ucblogo 5.1 or
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(setq logo-term-columns nn)
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(setq logo-term-rows mm)
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Where nn and mm is whatever makes you happy.
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By default logo-mode will indent continued lines in logo (edit) buffer
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when RET-urn key is pressed. To insert a newline without indenting use
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LFD (C-j) key. To reverse this behavior (reverse should probably be
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considered "normal" behavior), add this form.
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(setq logo-standard-indent t)
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By default logo-mode starts with syntax highlighting enabled. If you
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do not want it, set this:
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(setq logo-syntax-highlight nil)
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If you feel that the default syntax highlighting is slowing your system
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(setq logo-lazy-lock-mode t)
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By default logo-mode starts with novice command management enabled. If
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you don't want it set this:
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(setq logo-novice-management nil)
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By default logo-mode will start Logo process in setcursor mode. To
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change this permanently set:
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(setq logo-setcursor-start nil)
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Default text input mode in setcursor mode is set to overwrite. To
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change this permanently set:
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(setq logo-setcursor-overwrite nil)
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By default, the old text, after recalling the previous input in
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setcursor mode will be cleared to the end of the line. If that gets in
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(setq logo-setcursor-spaces-old n)
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where n is from 0 to any number. However, spaces are never pushed beyond
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By default two spaces are pushed ahead of end of the new input in
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setcursor mode. If that gets in your way, set this:
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(setq logo-setcursor-spaces-new n)
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where n is from 0 to any number. However, spaces are never pushed beyond
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If emacs lags behind during indenting Logo procedures, or simply when
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hitting return key (you must be working on a *very* slow system to
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notice this last one), add this form.
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(setq logo-unbalanced-distance 4096)
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On a very slow machine go down to 2048. By default, this is set to
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8192, but it is doubtful that you will ever write a single implicitly
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continued logo line that will be 8K long.
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If you have installed ucblogo info files translated into another language,
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(setq logo-info-file-trans "/your-info-path/file-name.info")
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However, for this to work - somebody has to write translation first. To the
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best of my knowledge only Croatian translation exists. Therefore by default
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this is set to "/usr/local/info/ucbl-hr.info" . If you change this to another
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language you must also update the `Help' menu entry by setting this:
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(setq logo-info-trans "(De)")
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This "(De)" would be in case your translation is German, but you can use
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longer words as well. By default this is set to "(Hr)".
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If you don't care for this at all, set
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(setq logo-info-trans nil)
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With this set menu entry for translated manual will disappear.
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By default emacs enables changes to Logo language through
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Logo>>Language, and Logo>>Compiler menus. This has to do with .loops
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initialization file. If you do not want to use this facility, set
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(setq logo-load-language nil)
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Logo mode automatically sets the depth of setcursor input history menu
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to safe value for the display resolution it is running on. (20 entries
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for 640x480, 25 for 800x600 ...) To change this set following:
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(setq logo-dynamic-menu-depth n)
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where n is any number (up to ... 48). However note that if you use
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larger number, (depending on your display resolution, and emacs font
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size) you may not be able to see nor use all menu entries.
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If you don't want me messing with your default emacs colors, then
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(setq dont-mess-with-logo-colors t)
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If you don't want parens matching on cursor movement, then set this line:
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(setq logo-flash-on-movement nil)
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If you want to change the delay after matching parentheses on cursor
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movement, set this to any number of seconds you wish:
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(setq logo-matching-delay-time seconds)
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Default delay is set to 2 seconds, but even a very long delay -- say,
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5 seconds would be OK, as you don't have to wait for it to
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complete. Delay will be reset if you move the cursor again.
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By default logo-mode starts with automatic expansion of common Logo
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abbreviations enabled, If you do not want this, set:
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(setq logo-expand-common-abbrevs nil)
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For those that are translating Logo primitive names into another
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language, (I know that the translation into French is underway), add
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this form to enable the expansion of new primitives:
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(define-abbrev-table 'logo-mode-abbrev-table
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of course, using your new names instead of those used here.
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4. There are several other options settable in .emacs file, but they
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deal mostly with problem corrections. If I have done my work properly,
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and if you have installed ucblogo (release 5.1 or newer) as instructed
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in ucblogo README file, they will not be necessary. Read logo.el file
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(first five pages) for the description of other options. (For instance
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if Emacs can't find Logo help files, debug menu doesn't work etc. ...)
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========================================
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USING BERKELEY LOGO WITH EMACS LOGO MODE
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========================================
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To start logo mode, open one Logo source file in emacs. As far as
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emacs is concerned Logo source file is the file that ends with .lg ,
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.lgo , or a file that has this `;;; -*- logo -*-' on a first line.
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Start ucblogo from a `Logo-start' menu. You can start Logo in `Other
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Frame',or `Same Window'. The *BEST* way is `Other Frame', and I
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definitely suggest using it. (The `Same Window' is given for archaic
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reasons only.) Due to availability of setcursor mode I insist on a
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minimum window (frame) size when Logo starts -- 81x26 (that is if the
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usable size is left at 80x24). Do not change frame size of Inferior
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Logo buffer (by dragging corners with the mouse), or Logo output will
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be garbled. On the other hand - stretching the height of Logo edit
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frame is perfectly OK.
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Editing and sending Logo source code:
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=====================================
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You write Logo code in Logo edit buffer. All standard emacs editing
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features are supported here. The notable difference from standard
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behavior is automatic indenting bound to RET (enter) key. You can
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check special Logo editing features by pulling down `Logo-edit'
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menu. All functions that are bound to a key sequence will show that
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sequence as well. To see commands for sending source code (or parts of
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it) to Logo, pull down `Logo-send' menu. Choices that are shaded (in
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all of these menus) denote that this option is presently not
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available. For instance if `Send Region' is shaded it simply means
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that no region has been selected.
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You can have several source files opened, but only one Logo process
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buffer. That is the reason for all three choices on `Logo-start' menu
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being shaded after you have started Logo.
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Syntax highlighting is turned on by default (unless you have disabled
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it in .emacs file). However you can always turn it off/on with `Toggle
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Syntax Highlighting' choice in `Logo-edit' pull-down menu.
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Following syntax classes are highlighted:
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Comments - (red) text.
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Strings - (brown) text.
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Start and end of Logo procedure definition (TO .MACRO DEFINE .DEFMACRO
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Variables (actually :var.name) - (light blue) text.
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Highlighting of beginning and end of Logo definitions is not so
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dependable as functions that mark procedure boundaries (used for code
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indenting and sending). TO, .MACRO, and END will not be highlighted if
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For `adventurous' novices (meaning mostly Emacs novices) I have
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included novice command management feature. This simply tags
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potentially dangerous commands, and they are not executed
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immediately. Instead, emacs will pop a window with warning, and basic
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instructions what to do next. You can still execute the command if you
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decide so. If you find this disturbing (I do) then turn it off with
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Logo-edit>>Preferences>>Toggle Novice Management choice from menu-bar,
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or set it permanently in .emacs file.
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Interacting with Logo:
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======================
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To run and test your procedures switch to Inferior Logo buffer. If you
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have started Logo in `Same Window', to switch -- you have to use
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`C-c l'. Otherwise simply move the mouse pointer to Logo buffer.
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The usual goodies from Scheme (or Lisp modes) are present in Logo mode
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as well. You can step with `M-p' / `M-n' (C-up / C-down, should also
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work, if not trapped by your Window Manager) through the previous
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inputs to Logo in all modes, and edit these inputs as you wish. When
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finished with editing (input) simply hit Return key wherever you are
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in the input line. Emacs will correctly grab the whole input and send
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it to Logo. You can use S-down-mouse-2 (shift and press mouse-2)
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anywhere on the Inferior Logo window to pop-up the `List Input
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History' menu. Release mouse on any of the entries, and that input
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will be inserted on command line.
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Several standard editing keys work "slightly" different in Inferior
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Logo mode. Delete and Backspace keys work only within current command
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(input) line. Kill and yank (paste) commands work only on input line,
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by killing or yanking the whole input. Do not bother aiming with the
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mouse accurately. No matter where you are in Inferior Logo buffer,
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mouse-2 will paste new input line, overwriting the old line. The old
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input is cleared, so don't try pasting two inputs hoping they will
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concatenate. You can not tell emacs where is the end of input line,
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by positioning the point there. That is chosen
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automatically. (Actually this is not entirely true -- if emacs ever
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gets hopelessly confused about the position of logo-input-marker, you
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can set it manually with `C-@'.) The whole purpose for this yanking
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(pasting) business is to transfer input lines from other applications
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running on your X display, therefore X-selection always takes
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precedence over emacs kill-ring. (To retrieve previous inputs from
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your current Logo/logo-mode session use `M-p' instead.)
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Probably the *most useful* key to remember in Inferior Logo mode is
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`C-l'. This is not bound to `recenter' as in the rest of logo-mode
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buffers, but to `logo-find-input-end' which takes you back to the end
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of Logo command line (in case you had wondered off).
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To stop a "runaway" Logo hit `C-c C-c' in Inferior Logo buffer. If this
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doesn't work use one of the choices from from `Signals' pull-down menu
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`BREAK' (`C-c C-c') to which Logo should respond with "Stopping..."
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`QUIT' to which Logo should respond with "Pausing..."
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`KILL' to which emacs responds with "Process logo killed"
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Signals menu is not part of logo.el, so there are no Logo specific
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choices there - it is built into comint mode.
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You do not have to worry (as you should if using Logo without
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logo-mode) about saving your source files before you test any of
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them. Even if Logo crashes in Inferior Logo buffer (with a message
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like ... segmentation fault ...), your sources are still intact in
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Logo edit buffer. Simply restart Logo with `Logo-start' menu, and
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re-send your procedures to it with any of the choices on `Logo-send'
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Workspace Management:
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=====================
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To choose procedures for tracing or stepping, use `Logo-debug'
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sub-menu under `Logo' pull-down menu in Inferior Logo buffer. Debug
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buffer lists all names currently defined, and lets you select
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procedures (variables or properties) for tracing or stepping. Mouse
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bindings are as in XFM. Mouse-1 selects only the pointed name
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(de-selects everything else), mouse-2 toggles the selection for the
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name, mouse-3 selects pointed name, quits debug-buffer and sends all
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selected names to Logo. `q' key also quits debug-buffer and sends all
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selected names to Logo. When you open `Trace...' or `Step...' menus,
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the names that were traced or stepped before will be highlighted (and
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placed in parentheses).
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The last entry under `Logo>>Logo-debug' menu is `Erase'. You can mark
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(with the same mechanism as for tracing); procedures, variables or
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plists for erasing. After `q' key is pressed, marked names will be
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erased from Logo workspace, and GC will run automatically. To check
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which is the buffer you're actually working with (trace, step or
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erase), as all three look alike -- read the buffer mode line. For
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erase buffer it will state: `(Fundamental Logo-ERASE View)' etc.
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Logo-mode has a very simple help system.
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Help works in source buffers. Press mouse-3 on any valid Logo name,
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and the help file (for that procedure) will open. To exit hit `q'. If
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the help for the procedure doesn't exist, HELPCONTENTS file will be
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opened. There you can choose as many help files as you want (with
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mouse-3). Hit `q' in HELPCONTENTS to return to the source file. If you
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want to check HELPCONTENTS, either click mouse-3 on a word which is not
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defined in Logo, or use `Logo-help' sub-menu on emacs `Help' pull-down
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menu. This option is available only on Logo edit frame menu bar.
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To get better organized and more comprehensive help, browse through
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Logo User Manual by pulling down the `Help' menu and choosing from
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`Logo-help' sub-menu, `User Manual'. That will work if you have
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installed ucblogo.info files (normally installed automatically). To
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exit from Logo User Manual buffer hit `q'.
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To get help for logo-mode itself hit `C-h m' in any of emacs logo mode
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Although completion facilities are not part of the help system, you
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can regard them as such. Two types of completion are available in logo
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edit buffers. Completion for Logo keywords (actually standardly
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defined names of Logo primitive and library procedures) and completion
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for words that were already used in any of opened logo edit buffers.
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To perform completion for Logo keywords write a few starting letters
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and hit ESC TAB. This will open a window with a list of all possible
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Logo keyword completions. Click mouse-2 on the one you want, and your
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keyword will be completed in edit buffer.
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To perform completion on a word that is not standardly defined Logo
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name (this works both in edit and Logo process buffers), write a few
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letters, and hit M-/ (Alt-/). If possible, emacs will complete the
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word with the word you have used before in this, or any other Logo
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buffer currently opened. If there are more possible completions,
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cycle through them by repeatedly pressing M-/, until you find the one
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you want. The other way to accomplish the same result is to hit C-M-/
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(Ctrl-Alt-/) and emacs will open a window with all available
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completions listed. Click mouse-2 on the one you want.
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Logo common abbreviations are expanded when one of these characters
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is entered after the word that constitutes abbreviation: space,
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newline, ], }, and ). To disable this in the current session click on
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Logo-Edit>>Preferences>>Toggle Abbreviation Expansion. You can
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reactivate expansion using the same menu. Current state of
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abbreviation expansion is visible on the mode line; if it reads
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(Logo), expansion is disabled, if it reads (Logo Abbrev) it is
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enabled. If you want to disable the expansion only on the current
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word, escape the character that triggers the expansion. E.g.: if you
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do not want to expand OP to OUTPUT after hitting space key, press
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escape key, and then the space key. The expansion will not occur this
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time, but next time you hit space after the abbreviation, the
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expansion will be carried out.
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Obvious *NOT To DOs* when running Logo in Logo mode:
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====================================================
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Entering `edit "whatever' in Inferior Logo buffer defeats the purpose
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of using Logo mode. Whatever you edit this way will be lost (unless you
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save it manually). You will not be able to use logo-mode editing
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features this way, even if your EDITOR environment variable is set to
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emacs. This will also block Logo -- no interaction from other
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logo-mode buffers will be possible.
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Entering `load "whatever' in Inferior Logo buffer is not the right way
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to do it. Use `Open Logo File...' choice from `Files>>Logo-mode Files'
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pull-down menu in Logo edit buffer. Emacs will pop-up a new frame
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(that is, if you started Logo with `Run Logo Other Frame') and drop it
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in a `Dired' mode, with default directory (the directory where the
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first source file resides) displayed. Then choose (mouse-2) the
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desired file. This way you can see both source files at the same
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time. To send this file to Logo, simply hit `C-c b'. If you opened
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Logo source file that neither has the `.lg' extension, nor Logo
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mode-line as the first line, use `Files>>Logo-mode Files>>Convert to
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Logo-mode' choice from the pull-down menu. (Only files opened in
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fundamental mode can be converted.)
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If you started Logo with `Run Logo Same Window' choice, you can still
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have several source files opened. Switch between them with `C-c l' key
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using prefix. (If you have three files opened `C-u 1 C-c l' switches
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from Inferior Logo buffer to the newest source buffer, and `C-u 3 C-c
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l' switches to the oldest buffer -- or just use emacs `Buffers' menu
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There is no need to use help, trace or step Logo commands
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manually. They can't hurt, but logo-mode provides interactive, mouse
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driven interface, which is easier to use.
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Do not define Logo procedures by typing them directly to Logo in
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Inferior Logo buffer. This will work OK, but you will not be able to
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change them later on. `M-p' will retrieve them line by line, and not
421
as a whole definition. Instead, simply enter definitions in Logo edit
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buffer and send them over with `C-M-x'. The key-chord C-M-x
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(Ctrl-Alt-x) will not always work, and as it is the most frequently
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used keyboard shortcut (much faster than using Send Definition from
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Logo-send menu), additional instructions are in order. Some window
426
managers (KDE 2.1 for instance) use this same combination for their
427
own purposes, and will therefore intercept this key-chord. You can
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still use Esc C-x combination (Esc always works in the place of Meta
429
or Alt key), but this is much slower that C-M-x. The only way to
430
restore the functionality of C-M-x in logo mode is to disable this key
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combination in the KDE Control Center.
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If you have been using SETCURSOR command in Inferior Logo mode, and
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Inferior Logo buffer is cluttered with old text, do *not* try to clear
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the buffer using emacs. Instead, use Logo to do the job -- enter `ct'
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(CLEARTEXT) command on Logo input line.
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Not so obvious *NOT To DOs*:
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============================
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Do not leave blank lines (spaces only) inside Logo string
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constants. Indenting and procedure sending functions in logo-mode depend
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on this. If you really need a blank line in Logo string, you can use this:
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As far as Logo is concerned, result is the same. Logo-mode, however will
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malfunction on the second.
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Although you can leave blank lines and comment lines (comments only)
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inside procedure definitions in Logo edit buffer, their use is
459
restricted to areas between lines that are not continued, or are
460
implicitly continued (Lisp style). Do not use blank lines between
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explicitly continued Logo lines (lines that end with `~'). Neither
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Logo, nor logo-mode function properly in these circumstances. You can
463
use comment only lines between two explicitly continued Logo lines, but
464
you must end them with `~'. However, you are on your own here -- in
465
some cases Logo will reject those.
467
This is what I was talking about:
477
(tree "France leaves [Paris Dijon Avignon])
480
(tree "China leaves [Beijing Shanghai Guangzhou Suzhou])
483
This works OK. However if you try to insert a comment line between
488
lines, Logo will print error message when worldtree is run.
491
Do not use names like `x\;y' `x\(y' `x| |y' `x|;|y' `x\\y' or some
492
such for your procedures and variables. Although Logo will accept
493
this, you will not be able to mark these names in Workspace Management
494
(Debug) buffer. I have allowed some rather weird characters to
495
accommodate Brian's MATCH program, but that's as far as I'll go.
498
Do not use yank (paste) facility to paste procedure definitions
499
directly to Inferior Logo buffer -- this will not work. Yank can be
500
used only to paste the command line (input) directly to Logo. This
501
probably sounds ambiguous, therefore one small example:
503
Let's say that you have in another editor window (it can be another
504
copy of emacs, or whatever) this procedure:
507
op filter [[x] [op or not equalp :e :x memberp :x ?rest]] :l
510
and you want to test it in current Logo/logo-mode session. If you yank
511
it directly to Inferior Logo buffer, it will arrive as one line
512
(setcursor mode), and Logo will not accept this as a procedure
513
definition. Instead, yank it to Logo edit buffer, and use `C-M-x'
516
On the other hand (once Logo has received the procedure definition),
517
you can use yank to paste from other editor test inputs to procedure
518
remove1. For instance, you can yank:
519
`show remove1 2 [1 2 3 1 2 3 1 2 3]'
520
directly to Inferior Logo buffer and hit return. Logo should respond
521
by printing following:
523
? show remove1 2 [1 2 3 1 2 3 1 2 3]
527
This is an oversimplified example, but, there will be times (when
528
testing tree recursive procedures -- for instance) where the test input
529
will be several lines long elaborately constructed tree list...
532
Do *not* try to close Logo by clicking on X in the upper right corner
533
of *logo* frame (or by using close option on the upper left corner of
534
the *logo* frame). This will close that frame, and make Logo
535
unaccessible to you, but it will *not* kill Logo. If you want to kill
536
Logo, type `bye' in *logo* buffer.
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Not so obvious *To DOs*:
540
========================
541
One of the facilities built into logo-mode is automatic loading of
542
.loops initialization file from your home directory - if it exists. The
543
idea here is not so much to write additions to Logo library (although
544
it can be used for that as well), but to alter the standard behavior
545
of Logo interpreter. The last version (v.0.9) adds LOOPS, a rudimentary
546
Logo Object Oriented Programming System (just an experiment).
548
As an example of what can be done with initialization file, copy the
549
included .loops (dot.loops) file to your home directory, and start
550
Logo. Click on `LOOPS>>Language>>Ucblogo + LOOPS' menu, and emacs will
551
load .loops extensions into Logo.
553
The Compiler sub-menu on Logo pull-down menu in Inferior Logo buffer
554
is LOOPS specific. To understand what it does, and -- indeed, how to
555
use LOOPS extensions click on `Help>>Logo-help>>LOOPS User Manual'.
556
*(Part of the LOOPS User Manual needs updating.)*
559
===============================
560
COMMENTS BUG REPORTS AND To-DOs
561
===============================
563
Logo-mode is tested only on Intel machines running Linux and
564
FreeBSD. I have no access to anything else. The original work started
565
on emacs 19.34.1(b), but that version is no longer supported.
566
Logo-mode v2.9 will work only with emacs 20.5 and newer. Your safest
567
bet is to upgrade to the latest version.
569
Right now I have a lot "To-DO", but am willing to listen to
570
"reasonable" suggestions.
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For more information, comments, or bug reports, send e-mail to
added
removed
emacs/README
