Feature request? print -e to eval ?

Feature request? print -e to eval ?

[Marc Chantreux]

hello people,
 
i don't know about you but i often eval something i just printed.
for exemple:

status_as_flag () { eval $( print -P "${1?flag name}=%(?.true.false)" ) }

when it would be nice to write

status_as_flag () { print -eP "${1?flag name}=%(?.true.false)" }

(no more subshell and more readable)

what to you think about the idea ?

regards
-- 
Marc Chantreux (eiro on github and freenode)
http://eiro.github.com/
http://eiro.github.com/atom.xml
"Don't believe everything you read on the Internet"
    -- Abraham Lincoln

Re: Feature request? print -e to eval ?

[Peter Stephenson]

On Tue, 5 Sep 2017 13:17:14 +0000
Marc Chantreux <khatar@phear.org> wrote:
> i don't know about you but i often eval something i just printed.
> for exemple:
> 
> status_as_flag () { eval $( print -P "${1?flag name}=%(?.true.false)" ) }
> 
> when it would be nice to write
> 
> status_as_flag () { print -eP "${1?flag name}=%(?.true.false)" }
> 
> (no more subshell and more readable)
> 
> what to you think about the idea ?

Have a look at the (%) flag to ${...}.  For example,

${(%):-'blah blah'}

substitues blah blah expanded as a prompt.  You can assign that and
print it.

In general, assigning a value then printing it and evaluating
it if you need is probably the way to go.

pws

Re: Feature request? print -e to eval ?

[Marc Chantreux]

hello,

> Have a look at the (%) flag to ${...}.

\o/ i missed it for so long ! thank you very much Peter.

the only one thing missing to make evalp obsolete is to defer the
interpolation of a variable

	command=(echo '%(?.true.false) $USER' ); ${(%):-$command}

isn't good because $USER in never interpolated (even if setopt promptsubst)
and of course, the "" are bad because it interpols as it sets up
$command.

i really would like to write something like:

	c=( echo 'dear $USER, you did it %(?.fine.wrong)' )
	${(%):-$c}

but again: the (%) tip is a perfect addition to my daily zsh toolkit.
thank you for that.

regards

-- 
Marc Chantreux (eiro on github and freenode)
http://eiro.github.com/
http://eiro.github.com/atom.xml
"Don't believe everything you read on the Internet"
    -- Abraham Lincoln