Re: Call for opinions on a couple of prospective zsh patches

[Peter Stephenson <pws@ibmth.df.unipi.it>]

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"Bart Schaefer" wrote:
> * Partial word motions in the face of mixed case, i.e. move the cursor to
>   the next/previous capital letter InMixedCaseWordsLikeThisOne, including
>   deletions that treat words this way.  This is also handled by adding a
>   few new ZLE builtins, and relies on isupper() to detect upper case, so
>   it may behave differently in different language locales.
> 
>   My first inclination was to think that this should be handled with the
>   WORDCHARS variable, but of course WORDCHARS adds other characters that
>   are treated as alphanumeric; there's no way to say that upper case
>   letters should -not- be treated as alphanumeric.  I guess I'd prefer a
>   patch that handled wordchar-exlusions more generically (without adding
>   builtins) and I may even look at adding such a thing.
> 
>   For this patch to go into 3.0.6, I'd want PWS to agree that the new ZLE
>   builtins would appear in 3.1.6, too.

Well, in 3.1 you can do more sophisticated things by altering $CURSOR with
widgets already, so new builtins are not really necessary.  Furthermore,
getting a complete set of functions with this alternative word behaviour
looks a slightly wasteful way of doing it (and if it's an incomplete set of
functions, I guarantee it won't have the one you want).

But it would be nice to have some advance on $WORDCHARS, which has always
frustrated me (I always wanted to be able to specify characters which
*shouldn't* be parts of words, since $WORDCHARS is too long for me to see
easily what's not in it --- and how else can I tell the code that only
spaces should delimit words; and why does the default include =, - and /
but not +; parentheses but not |?  Etc.).

Perhaps the solution to the problem in question is to add a variable
$WORDSTART giving a list of characters with this behaviour, and the
corresponding macro iwords().  It could allow ranges, so you can add "A-Z";
the change to inittyptab() to allow that isn't too drastic --- the change
to zle_word.c is the hairy one.  That's less sophisticated w.r.t. locales,
unfortunately; you'd have to add ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞ by hand,
which is a little unpleasant.  An alternative is to allow A to stand for
all upper case, 1 for all digits, etc; or to allow escape sequences, so \\
-> backslash, \U -> uppercase, etc (that's perhaps the neatest).  I don't
see an easy way of avoiding a new variable by enhancing $WORDCHARS, since in
principle anything can appear in that.  You could, say, have a list of
possible initial characters after two spaces, but it's a bit of a mess.

Perhaps, if my frustrations above are widespread, there's room for a
variable $NONWORDCHARS, too.  That's easy to add: by default it's not set,
and if it is it takes precedence over $WORDCHARS in inittyptab() so that
anything not in it is made a word character; no editing code needs to
change.  Can this be made to the job of $WORDSTART?  It seems to me not,
since forward-word puts the cursor *after* the non-word character, which
isn't what you want with special initial characters (they're behaving more
like special final characters, in fact).

-- 
Peter Stephenson <pws@ibmth.df.unipi.it>       Tel: +39 050 844536
WWW:  http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56127 Pisa, Italy