Re: How to avoid infinite recursion in ZLE widgets

["Peter Slížik" <peter.slizik@gmail.com>]

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Thanks, Daniel!

Peter

сре, 23. сеп 2020. у 13:29 Daniel Shahaf <d.s@daniel.shahaf.name> је
написао/ла:

> Peter Slížik wrote on Wed, 23 Sep 2020 10:34 +0200:
> > Hello,
> >
> > I'd like to replicate the functionality found in some text editors -
> namely
> > that if you press a single or double quote, the editor inserts two of
> them
> > and places the cursor inside the pair.
> >
> > With some necessary checks for word boundaries, etc. left out, the
> solution
> > looks rather trivial:
> >
> > function insert-single-quotes() {
> >     zle self-insert "''"    # that's "_'_'_"
> >     zle backward-char
> > }
> >
> > zle -N insert-single-quotes
> > bindkey "'" insert-single-quotes    # that's "_'_"
> >
> > However, this solution creates infinite recursion (a single quote bound
> to
> > insert a single quote).
>
> No, it doesn't.  I tried in «zsh -f» and it inserts a single quote
> without moving the cursor.
>
> It inserts _one_ quote, rather than two, because self-insert ignores
> its positional arguments and the widget was bound to «'».
>
> > 1. How to prevent the recursion?
>
> Always open a new shell for testing.
>
> > Is self-insert the right widget for this task?
>
> You could also use «zle .self-insert», or even modify $LBUFFER and
> $RBUFFER directly («LBUFFER+=\'; RBUFFER=\'$RBUFFER»).
>
> (Incidentally, I guess you may also want to check whether ${RBUFFER}
> starts with a single quote, but that's no longer a zsh question but
> a business logic question.)
>
> > 2. I played with zle -U. What are the use cases for zle self-insert and
> zle
> > -U?
>
> «zle -U foo» subjects the «f», «o», and «o» to bindkey mappings.  For
> instance, «bindkey -s x y» followed by «zle -U x» would insert «y».
>
> «self-insert» appends one character to the buffer.
>
> > 3. I tried to avoid the recursion by using "zle -K .safe -U text", but it
> > ended with "too many arguments for -K". How is zle -K expected to be
> used?
>
> As «zle -K foo» without further arguments.  You can do something like this:
>
>     {
>         readonly save_KEYMAP=$KEYMAP
>         zle -K .safe
>         ⋮
>     } always {
>         zle -K $save_KEYMAP
>     }
>
> But see above about $LBUFFER.
>
> Cheers,
>
> Daniel
>

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