Re: Array as parameter

Re: Array as parameter

[Stephane CHAZELAS]

2011-11-1, 22:00(-07), Wayne Davison:
> --000e0cd299861c09c804b0b95bb8
> Content-Type: text/plain; charset=UTF-8
>
> On Tue, Nov 1, 2011 at 8:35 PM, <meino.cramer@gmx.de> wrote:
>
>>    arrprint a
>>
>
> That passes the string "a" to the function.  One thing you can do is to
> pass the array as separate parameters (arrprint $a)

$a discards the empty elements in the "a" array. Use "${a[@]}"
instead.

> and then use "for i in
> $*" in your function

$* in zsh also discards the empty elements (it's even worse in
compatibility mode with other shells where word splitting and
filename generation may also be done). Use "$@" instead. Or
better, write it "for i do".

> However, if you need to be able to keep the array
> parameter separate from other parameters, you could instead refer to the
> variable whose name you passed in using ${(P)1} in your function in place
> of the $1.

Except that it doesn't work for arrays. You'd need to  use eval
here.

-- 
Stephane

Re: Array as parameter

[Mikael Magnusson]

On 2 November 2011 10:10, Stephane CHAZELAS <stephane_chazelas@yahoo.fr> wrote:
> 2011-11-1, 22:00(-07), Wayne Davison:
>> However, if you need to be able to keep the array
>> parameter separate from other parameters, you could instead refer to the
>> variable whose name you passed in using ${(P)1} in your function in place
>> of the $1.
>
> Except that it doesn't work for arrays. You'd need to  use eval
> here.

(P) works perfectly fine with arrays.

-- 
Mikael Magnusson

Re: Array as parameter

[Stephane Chazelas]

2011-11-02 11:14:38 +0100, Mikael Magnusson:
> On 2 November 2011 10:10, Stephane CHAZELAS <stephane_chazelas@yahoo.fr> wrote:
> > 2011-11-1, 22:00(-07), Wayne Davison:
> >> However, if you need to be able to keep the array
> >> parameter separate from other parameters, you could instead refer to the
> >> variable whose name you passed in using ${(P)1} in your function in place
> >> of the $1.
> >
> > Except that it doesn't work for arrays. You'd need to  use eval
> > here.
> 
> (P) works perfectly fine with arrays.
[...]

Indeed, though it seems you have to write it as "${${(@P)1}[@]}", I'm not too sure why.

~/install/cvs/pixz$ zsh -c 'a=("" "a b" c d); b=a; print -l "${${(P)b}[@]}"'
 a b c d
~/install/cvs/pixz$ zsh -c 'a=("" "a b" c d); b=a; print -l "${${(@P)b}[@]}"'

a b
c
d

-- 
Stephane

Re: Array as parameter

[Mikael Magnusson]

On 2 November 2011 13:06, Stephane Chazelas <stephane_chazelas@yahoo.fr> wrote:
> 2011-11-02 11:14:38 +0100, Mikael Magnusson:
>> On 2 November 2011 10:10, Stephane CHAZELAS <stephane_chazelas@yahoo.fr> wrote:
>> > 2011-11-1, 22:00(-07), Wayne Davison:
>> >> However, if you need to be able to keep the array
>> >> parameter separate from other parameters, you could instead refer to the
>> >> variable whose name you passed in using ${(P)1} in your function in place
>> >> of the $1.
>> >
>> > Except that it doesn't work for arrays. You'd need to  use eval
>> > here.
>>
>> (P) works perfectly fine with arrays.
> [...]
>
> Indeed, though it seems you have to write it as "${${(@P)1}[@]}", I'm not too sure why.

You need to specify @ at every nesting level that's inside double
quotes to prevent scalar joining. At the ${(P)b[@]} level, if that was
an implied question, the subscript is applied first:


> ~/install/cvs/pixz$ zsh -c 'a=("" "a b" c d); b=a; print -l "${${(P)b}[@]}"'
>  a b c d
> ~/install/cvs/pixz$ zsh -c 'a=("" "a b" c d); b=a; print -l "${${(@P)b}[@]}"'
>
> a b
> c
> d

But this is shorter,
% zsh -c 'a=("" "a b" c d); b=a; print -l "${(@P)b}"'

a b
c
d


-- 
Mikael Magnusson

Re: Array as parameter

[Mikael Magnusson]

On 2 November 2011 13:13, Mikael Magnusson <mikachu@gmail.com> wrote:
> On 2 November 2011 13:06, Stephane Chazelas <stephane_chazelas@yahoo.fr> wrote:
>> 2011-11-02 11:14:38 +0100, Mikael Magnusson:
>>> On 2 November 2011 10:10, Stephane CHAZELAS <stephane_chazelas@yahoo.fr> wrote:
>>> > 2011-11-1, 22:00(-07), Wayne Davison:
>>> >> However, if you need to be able to keep the array
>>> >> parameter separate from other parameters, you could instead refer to the
>>> >> variable whose name you passed in using ${(P)1} in your function in place
>>> >> of the $1.
>>> >
>>> > Except that it doesn't work for arrays. You'd need to  use eval
>>> > here.
>>>
>>> (P) works perfectly fine with arrays.
>> [...]
>>
>> Indeed, though it seems you have to write it as "${${(@P)1}[@]}", I'm not too sure why.
>
> You need to specify @ at every nesting level that's inside double
> quotes to prevent scalar joining. At the ${(P)b[@]} level, if that was
> an implied question, the subscript is applied first:

[apparently some keycombo i just pressed sends the message in gmail, i
wonder what it was]

% zsh -c 'a=("" "a b" c d); b=(b a); print -l "${(@P)b[2]}"'

a b
c
d
% zsh -c 'a=("" "a b" c d); b=(b a); print -l "${(@P)b[1]}"'
b
a


>> ~/install/cvs/pixz$ zsh -c 'a=("" "a b" c d); b=a; print -l "${${(P)b}[@]}"'
>>  a b c d
>> ~/install/cvs/pixz$ zsh -c 'a=("" "a b" c d); b=a; print -l "${${(@P)b}[@]}"'
>>
>> a b
>> c
>> d
>
> But this is shorter,
> % zsh -c 'a=("" "a b" c d); b=a; print -l "${(@P)b}"'
>
> a b
> c
> d


-- 
Mikael Magnusson

Re: Array as parameter

[Stephane CHAZELAS]

2011-11-2, 04:35(+01), meino.cramer@gmx.de:
> how can I use an array as a parameter to a function like
> this (example does not work...just as an explanation, what
> I want to do)
>
>     #! /bin/zsh
>     funcion arrprint()
>     {
>         for i in $1
>         do
>             echo $i
>             echo "---"
>         done
>     }
>
>     a=( 1 2 3 4 5 6 )
>
>     arrprint a 
[...]

Try (pass by values)

arrprint() {
  for i do
    echo "$i"
    echo ---
  done
}
arrprint "${a[@]}"

Or (pass by name)

arrprint() {
  eval 'set -- "${'$1'[@]}"'
  for i do
    echo "$i"
    echo ---
  done
}
arrprint a

-- 
Stephane