Sundry Completion Questions ($_ $(^^) $(!!:s//)

Sundry Completion Questions ($_ $(^^) $(!!:s//)

[Sonny Michaud]

Good evening!

I have a few questions regarding some different completion mechanisms in 
zsh.

1) I noticed that $_<TAB> does not expand.  I am wondering if other 
parameter substitutions do expand and, if so, if there is an equivalent 
for $_ that is similarly pithy.  If not, is this something that deserves 
a feature request?

2) Quick history substitution does not expand in subcommands.  For 
instance, the following example does nothing.  I am not sure if this is 
also something that would warrant a feature request.
$ touch foo
$ echo $(^touch^cat)

3) Since the above does not work, I usually use $(!!:s/foo/bar), which 
has bizarre behavior, depending on whether or not a trailing slash is 
provided. This one feels like a bug proper, but it may have something to 
do with what I am attempting in particular.

$ grep -r foo
$ vim $(!!:s/-r/-rl)<TAB> -> vim $(grep -rl) foo

whereas

$ grep -r foo
$ vim $(!!:s/-r/-rl/)<TAB> -> $ vim $(grep -rl foo)

If anyone has any thoughts or suggestions about this, I would really 
appreciate the feedback.  Thanks!

- Sonny

Re: Sundry Completion Questions ($_ $(^^) $(!!:s//)

[Bart Schaefer]

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On Nov 1, 2014 5:39 PM, "Sonny Michaud" <michaud.sonny@gmail.com> wrote:
>
> 1) I noticed that $_<TAB> does not expand.

It expands for me.  It doesn't expand to anything very useful, because its
value changes during the execution of the completion functions, but it does
expand.

Do you have _expand in your "completer" zstyle?

> 2) Quick history substitution does not expand in subcommands.

Quick history substitution is a command-line construct, not a command
syntax construct.  It only works when the quick-history character appears
as the first character of the input buffer.

> 3) Since the above does not work, I usually use $(!!:s/foo/bar), which
has bizarre behavior, depending on whether or not a trailing slash is
provided.

History syntax doesn't interact with shell command syntax in the way you
are expecting.  *Everything* after the second slash, *including* the
closing paren, is part of the history reference unless you close the
history syntax by adding the third slash.

History substitution is a purely lexical replacement which occurs before
any shell-syntax analysis of the input is performed.

Re: Sundry Completion Questions ($_ $(^^) $(!!:s//)

[Sonny Michaud]

Thanks for the response, it really clarifies a lot.  I did not have 
_expand in my completer, but I see how it ends up producing gibberish.

On 11/01/2014 10:08 PM, Bart Schaefer wrote:
> On Nov 1, 2014 5:39 PM, "Sonny Michaud" <michaud.sonny@gmail.com> wrote:
>> 1) I noticed that $_<TAB> does not expand.
> It expands for me.  It doesn't expand to anything very useful, because its
> value changes during the execution of the completion functions, but it does
> expand.
>
> Do you have _expand in your "completer" zstyle?
>
>> 2) Quick history substitution does not expand in subcommands.
> Quick history substitution is a command-line construct, not a command
> syntax construct.  It only works when the quick-history character appears
> as the first character of the input buffer.
>
>> 3) Since the above does not work, I usually use $(!!:s/foo/bar), which
> has bizarre behavior, depending on whether or not a trailing slash is
> provided.
>
> History syntax doesn't interact with shell command syntax in the way you
> are expecting.  *Everything* after the second slash, *including* the
> closing paren, is part of the history reference unless you close the
> history syntax by adding the third slash.
>
> History substitution is a purely lexical replacement which occurs before
> any shell-syntax analysis of the input is performed.
>