-u option does not work with recursive expansion?

-u option does not work with recursive expansion?

[Dominik Vogt]

Why does the recursive expansion of foo not trigger an error
message with the -u option?  Is that a bug?  Is there some
woraround to get the expected error behaviour in all cases?

-- snip --
set -u
foo=bar
unset bar
# ==> bar: parameter not set
echo $bar
# ==> no error?
echo ${${foo}}
-- snip --

 $ zsh --version
 zsh 5.3.1 (x86_64-...-...-gnu)

Ciao

Dominik ^_^  ^_^

-- 

Dominik Vogt

Re: -u option does not work with recursive expansion?

[Mikael Magnusson]

On 2/15/19, Dominik Vogt <dominik.vogt@gmx.de> wrote:
> Why does the recursive expansion of foo not trigger an error
> message with the -u option?  Is that a bug?  Is there some
> woraround to get the expected error behaviour in all cases?
>
> -- snip --
> set -u
> foo=bar
> unset bar
> # ==> bar: parameter not set
> echo $bar
> # ==> no error?
> echo ${${foo}}
> -- snip --

If the above command doesn't output bar, your shell is very broken. I
think you're confused about what ${${foo}} means though. Putting a ${}
inside another ${} doesn't perform indirect expansion, you need (P)
for that.

-- 
Mikael Magnusson

Re: -u option does not work with recursive expansion?

[Dominik Vogt]

On Fri, Feb 15, 2019 at 12:45:28AM +0100, Mikael Magnusson wrote:
> On 2/15/19, Dominik Vogt <dominik.vogt@gmx.de> wrote:
> > Why does the recursive expansion of foo not trigger an error
> > message with the -u option?  Is that a bug?  Is there some
> > woraround to get the expected error behaviour in all cases?
> >
> > -- snip --
> > set -u
> > foo=bar
> > unset bar
> > # ==> bar: parameter not set
> > echo $bar
> > # ==> no error?
> > echo ${${foo}}
> > -- snip --
> 
> If the above command doesn't output bar, your shell is very broken. I
> think you're confused about what ${${foo}} means though. Putting a ${}
> inside another ${} doesn't perform indirect expansion, you need (P)
> for that.

Yeah, you're right.  My memory believes this was different at some
distant point in the past, i.e. that ${${A}} used to do recursive
expansion.

Well, with (P) it's possible to do recursive expansion at the
right side of an assigntment, but can you also do soething like

foo=bar
${foo}=baz

i.e. treat the contents of foo as the lvalue of an assignment?
(Without using eval, of course.)

Ciao

Dominik ^_^  ^_^

-- 

Dominik Vogt

Re: -u option does not work with recursive expansion?

[Bart Schaefer]

On Thu, Feb 14, 2019 at 4:47 PM Dominik Vogt <dominik.vogt@gmx.de> wrote:
>
> Well, with (P) it's possible to do recursive expansion at the
> right side of an assigntment, but can you also do soething like
>
> foo=bar
> ${foo}=baz
>
> i.e. treat the contents of foo as the lvalue of an assignment?

Not directly, but you can do

typeset ${foo}=baz

Re: -u option does not work with recursive expansion?

[Matthew Martin]

On Thu, Feb 14, 2019 at 6:47 PM Dominik Vogt <dominik.vogt@gmx.de> wrote:

>
> Well, with (P) it's possible to do recursive expansion at the
> right side of an assigntment, but can you also do soething like
>
> foo=bar
> ${foo}=baz
>
> i.e. treat the contents of foo as the lvalue of an assignment?
> (Without using eval, of course.)

% foo=bar; : ${(P)foo::=baz}; typeset -p bar
typeset bar=baz