viper: Movement and Markers
2.8 Movement and Markers
========================
Viper can be set free from the line-limited movements in Vi, such as ‘l’
refusing to move beyond the line, <ESC> moving one character back, etc.
These derive from Ex, which is a line editor. If your Viper
customization file contains
(setq viper-ex-style-motion nil)
the motion will be a true screen editor motion. One thing you must then
watch out for is that it is possible to be on the end-of-line character.
The keys ‘x’ and ‘%’ will still work correctly, i.e., as if they were on
the last character.
The word-movement commands ‘w’, ‘e’, etc., and the associated
deletion/yanking commands, ‘dw’, ‘yw’, etc., can be made to understand
Emacs syntax tables. If the variable ‘viper-syntax-preference’ is set
to ‘strict-vi’ then the meaning of _word_ is the same as in Vi.
However, if the value is ‘reformed-vi’ (the default) then the
alphanumeric symbols will be those specified by the current Emacs syntax
table (which may be different for different major modes) plus the
underscore symbol ‘_’, minus some non-word symbols, like ’.;,|, etc.
Both ‘strict-vi’ and ‘reformed-vi’ work close to Vi in traditional
cases, but ‘reformed-vi’ does a better job when editing text in
non-Latin alphabets.
The user can also specify the value ‘emacs’, which would make Viper
use exactly the Emacs notion of word. In particular, the underscore may
not be part of a word. Finally, if ‘viper-syntax-preference’ is set to
‘extended’, Viper words would consist of characters that are classified
as alphanumeric _or_ as parts of symbols. This is convenient for
writing programs and in many other situations.
‘viper-syntax-preference’ is a local variable, so it can have
different values for different major modes. For instance, in
programming modes it can have the value ‘extended’. In text modes where
words contain special characters, such as European (non-English)
letters, Cyrillic letters, etc., the value can be ‘reformed-vi’ or
‘emacs’.
Changes to ‘viper-syntax-preference’ should be done in the hooks to
various major modes by executing ‘viper-set-syntax-preference’ as in the
following example:
(viper-set-syntax-preference nil "emacs")
The above discussion of the meaning of Viper’s words concerns only
Viper’s movement commands. In regular expressions, words remain the
same as in Emacs. That is, the expressions ‘\w’, ‘\>’, ‘\<’, etc., use
Emacs’s idea of what is a word, and they don’t look into the value of
variable ‘viper-syntax-preference’. This is because Viper doesn’t
change syntax tables in fear of upsetting the various major modes that
set these tables.
Textmarkers in Viper remember the file and the position, so that you
can switch files by simply doing ‘'a’. If you set up a regimen for
using Textmarkers, this is very useful. Contents of textmarkers can be
viewed by ‘[marker’. (Contents of registers can be viewed by
‘]register’).
Info Catalog
viper: Abbreviation Facilities
viper: Improvements over Vi
viper: New Commands