3.1 Rudimentary Changes

An easy way to customize Viper is to change the values of constants used in Viper. Here is the list of the constants used in Viper and their default values. The corresponding :se command is also indicated. (The symbols t and nil represent “true” and “false” in Lisp).

Viper supports both the abbreviated Vi variable names and their full names. Variable completion is done on full names only. TAB and SPC complete variable names. Typing = will complete the name and then will prompt for a value, if applicable. For instance, :se au SPC will complete the command to :set autoindent; :se ta SPC will complete the command and prompt further like this: :set tabstop = . However, typing :se ts SPC will produce a “No match” message because ts is an abbreviation for tabstop and Viper supports completion on full names only. However, you can still hit RET or =, which will complete the command like this: :set ts = and Viper will be waiting for you to type a value for the tabstop variable. To get the full list of Vi variables, type :se SPC TAB.

viper-auto-indent nil

:se ai (:se autoindent)

:se ai-g (:se autoindent-global)

If t, enable auto indentation. by RET, o or O command.

viper-auto-indent is a local variable. To change the value globally, use setq-default. It may be useful for certain major modes to have their own values of viper-auto-indent. This can be achieved by using setq to change the local value of this variable in the hooks to the appropriate major modes.

:se ai changes the value of viper-auto-indent in the current buffer only; :se ai-g does the same globally.

viper-electric-mode t

If not nil, auto-indentation becomes electric, which means that RET, O, and o indent cursor according to the current major mode. In the future, this variable may control additional electric features.

This is a local variable: setq changes the value of this variable in the current buffer only. Use setq-default to change the value in all buffers.

viper-case-fold-search nil

:se ic (:se ignorecase)

If not nil, search ignores cases. This can also be toggled by quickly hitting / twice.

viper-re-search nil

:se magic

If not nil, search will use regular expressions; if nil then use vanilla search. This behavior can also be toggled by quickly hitting / trice.

buffer-read-only

:se ro (:se readonly)

Set current buffer to read only. To change globally put (setq-default buffer-read-only t) in your .emacs file.

blink-matching-paren t

:se sm (:se showmatch)

Show matching parens by blinking cursor.

tab-width t (default setting via setq-default)

:se ts=value (:se tabstop=value)

:se ts-g=value (:se tabstop-global=value)

tab-width is a local variable that controls the width of the tab stops. To change the value globally, use setq-default; for local settings, use setq.

The command :se ts sets the tab width in the current buffer only; it has no effect on other buffers.

The command :se ts-g sets tab width globally, for all buffers where the tab is not yet set locally, including the new buffers.

Note that typing TAB normally doesn’t insert the tab, since this key is usually bound to a text-formatting function, indent-for-tab-command (which facilitates programming and document writing). Instead, the tab is inserted via the command viper-insert-tab, which is bound to S-tab (shift + tab).

On some non-windowing terminals, Shift doesn’t modify the TAB key, so S-tab behaves as if it were TAB. In such a case, you will have to bind viper-insert-tab to some other convenient key.

viper-shift-width 8

:se sw=value (:se shiftwidth=value)

The number of columns shifted by > and < commands.

viper-search-wrap-around t

:se ws (:se wrapscan)

If not nil, search wraps around the end/beginning of buffer.

viper-search-scroll-threshold 2

If search lands within this many lines of the window top or bottom, the window will be scrolled up or down by about 1/7-th of its size, to reveal the context. If the value is negative, don’t scroll.

viper-tags-file-name "TAGS"

The name of the file used as the tag table.

viper-re-query-replace nil

If not nil, use reg-exp replace in query replace.

viper-want-ctl-h-help nil

If not nil, C-h is bound to help-command; otherwise, C-h is bound as usual in Vi.

viper-vi-style-in-minibuffer t

If not nil, Viper provides a high degree of compatibility with Vi insert mode when you type text in the minibuffer; if nil, typing in the minibuffer feels like plain Emacs.

viper-no-multiple-ESC t

If you set this to nil, you can use ESC as Meta in Vi state. Normally, this is not necessary, since graphical displays have separate Meta keys (usually on each side of the space bar). On a dumb terminal, Viper sets this variable to twice, which is almost like nil, except that double ESC beeps. This, too, lets ESC to be used as a Meta.

viper-fast-keyseq-timeout 200

Key sequences separated by this many milliseconds are treated as Vi-style keyboard macros. If the key sequence is defined as such a macro, it will be executed. Otherwise, it is processed as an ordinary sequence of typed keys.

Setting this variable too high may slow down your typing. Setting it too low may make it hard to type macros quickly enough.

viper-ex-style-motion t

Set this to nil, if you want l,h to cross lines, etc. See Movement and Markers, for more info.

viper-ex-style-editing t

Set this to nil, if you want C-h and DEL to not stop at the beginning of a line in Insert state, X and x to delete characters across lines in Vi command state, etc.

viper-ESC-moves-cursor-back t

It t, cursor moves back 1 character when switching from insert state to vi state. If nil, the cursor stays where it was before the switch.

viper-always t

t means: leave it to Viper to decide when a buffer must be brought up in Vi state, Insert state, or Emacs state. This heuristics works well in virtually all cases. nil means you either has to invoke viper-mode manually for each buffer (or you can add viper-mode to the appropriate major mode hooks using viper-load-hook).

This option must be set in your Viper customization file.

viper-custom-file-name "~/.emacs.d/viper"

File used for Viper-specific customization. Change this setting, if you want. Must be set in .emacs before Viper is loaded. Note that you have to set it as a string inside double quotes.

viper-spell-function 'ispell-region

Function used by the command #c<move> to spell.

viper-glob-function

The value of this variable is the function symbol used to expand wildcard symbols. This is platform-dependent. The default tries to set this variable to work with most shells, MS Windows, OS/2, etc. However, if it doesn’t work the way you expect, you should write your own. Use viper-glob-unix-files and viper-glob-mswindows-files in viper-util.el as examples.

This feature is used to expand wildcards in the Ex command :e. Note that Viper doesn’t support wildcards in the :r and :w commands, because file completion is a better mechanism.

ex-cycle-other-window t

If not nil, :n and :b will cycle through files in another window, if one exists.

ex-cycle-through-non-files nil

:n does not normally cycle through buffers. Set this to get buffers also.

viper-want-emacs-keys-in-insert

This is set to nil for user levels 1 and 2 and to t for user levels 3 and 4. Users who specify level 5 are allowed to set this variable as they please (the default for this level is t). If set to nil, complete Vi compatibility is provided in Insert state. This is really not recommended, as this precludes you from using language-specific features provided by the major modes.

viper-want-emacs-keys-in-vi

This is set to nil for user level 1 and to t for user levels 2–4. At level 5, users are allowed to set this variable as they please (the default for this level is t). If set to nil, complete Vi compatibility is provided in Vi command state. Setting this to nil is really a bad idea, unless you are a novice, as this precludes the use of language-specific features provided by the major modes.

viper-keep-point-on-repeat t

If not nil, point is not moved when the user repeats the previous command by typing a period. This is very useful for doing repeated changes with the . key.

viper-repeat-from-history-key 'f12

Prefix key used to invoke the macros f12 1 and f12 2 that repeat the second-last and the third-last destructive command. Both these macros are bound (as Viper macros) to viper-repeat-from-history, which checks the second key by which it is invoked to see which of the previous commands to invoke. Viper binds f12 1 and f12 2 only, but the user can bind more in his/her Viper customization file. See Vi Macros, for how to do this.

viper-keep-point-on-undo nil

If not nil, Viper tries to not move point when undoing commands. Instead, it will briefly move the cursor to the place where change has taken place. However, if the undone piece of text is not seen in window, then point will be moved to the place where the change took place. Set it to t and see if you like it better.

viper-delete-backwards-in-replace nil

If not nil, DEL key will delete characters while moving the cursor backwards. If nil, the cursor will move backwards without deleting anything.

viper-replace-overlay-face 'viper-replace-overlay-face

On a graphical display, Viper highlights replacement regions instead of putting a ‘$’ at the end. This variable controls the so called face used to highlight the region.

By default, viper-replace-overlay-face underlines the replacement on monochrome displays and also lays a stipple over them. On color displays, replacement regions are highlighted with color.

If you know something about Emacs faces and don’t like how Viper highlights replacement regions, you can change viper-replace-overlay-face by specifying a new face. (Emacs faces are described in the Emacs Lisp reference.) On a color display, the following customization method is usually most effective:

(set-face-foreground viper-replace-overlay-face "DarkSlateBlue")
(set-face-background viper-replace-overlay-face "yellow")

For a complete list of colors available to you, evaluate the expression (x-defined-colors). (Type it in the buffer *scratch* and then hit the C-j key.

viper-replace-overlay-cursor-color "Red"

Cursor color when it is inside the replacement region. This has effect only on color displays and only when Emacs runs as an X application.

viper-insert-state-cursor-color nil

If set to a valid color, this will be the cursor color when Viper is in insert state.

viper-emacs-state-cursor-color nil

If set to a valid color, this will be the cursor color when Viper is in emacs state.

viper-replace-region-end-delimiter "$"

A string used to mark the end of replacement regions. It is used only on TTYs or if viper-use-replace-region-delimiters is non-nil.

viper-replace-region-start-delimiter ""

A string used to mark the beginning of replacement regions. It is used only on TTYs or if viper-use-replace-region-delimiters is non-nil.

viper-use-replace-region-delimiters

If non-nil, Viper will always use viper-replace-region-end-delimiter and viper-replace-region-start-delimiter to delimit replacement regions, even on color displays (where this is unnecessary). By default, this variable is non-nil only on TTYs or monochrome displays.

viper-allow-multiline-replace-regions t

If non-nil, multi-line text replacement regions, such as those produced by commands c55w, 3C, etc., will stay around until the user exits the replacement mode. In this variable is set to nil, Viper will emulate the standard Vi behavior, which supports only intra-line replacement regions (and multi-line replacement regions are deleted).

viper-toggle-key "\C-z"

Specifies the key used to switch from Emacs to Vi and back. Must be set in your Viper customization file. This variable can’t be changed interactively after Viper is loaded.

In Insert state, this key acts as a temporary escape to Vi state, i.e., it will set Viper up so that the very next command will be executed as if it were typed in Vi state.

viper-buffer-search-char nil

Key used for buffer search. See Viper Specials, for details.

viper-surrounding-word-function 'viper-surrounding-word

The value of this variable is a function name that is used to determine what constitutes a word clicked upon by the mouse. This is used by mouse search and insert.

viper-search-face 'viper-search-face

Variable that controls how search patterns are highlighted when they are found.

viper-vi-state-hook nil

List of parameterless functions to be run just after entering the Vi command state.

viper-insert-state-hook nil

Same for Insert state. This hook is also run after entering Replace state.

viper-replace-state-hook nil

List of (parameterless) functions called just after entering Replace state (and after all viper-insert-state-hook).

viper-emacs-state-hook nil

List of (parameterless) functions called just after switching from Vi state to Emacs state.

viper-load-hook nil

List of (parameterless) functions called just after loading Viper. This is the last chance to do customization before Viper is up and running.

You can reset some of these constants in Viper with the Ex command :set (when so indicated in the table). Or you can include a line like this in your Viper customization file:

(setq viper-case-fold-search t)