local arrays

local arrays

[Phil Pennock]

Is there a way in zsh-3.0.5 (or zsh-3.1.x) to use one command to declare
a variable to be both local and an array?

I can do
 local foo; set -A foo a b c
which does create a local array, but can't see a way to do this
manually.  And since there's no typeset for it ...

Thanks
-- 
--> Phil Pennock ; GAT d- s+:+ a23 C++(++++) UL++++/I+++/S+++/H+ P++@ L+++
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Re: local arrays

[Bart Schaefer]

On Jan 13, 10:12am, Phil Pennock wrote:
} Subject: local arrays
}
} Is there a way in zsh-3.0.5 (or zsh-3.1.x) to use one command to declare
} a variable to be both local and an array?

No, there isn't.  This is even documented, poorly (a bit better in pws-4,
because it was part of my rewrite of the `typeset' documentation).

Why do you need to do this?  The variable will assume array-ness upon the
first array assignment to it.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Re: local arrays

[Peter Stephenson]

Phil Pennock wrote:
> The scripts I write are liable to be modified by others.  So the purpose
> of stuff should be clear.  Nice clean explicit statements of what a
> variable is help.  So integers get declared as such, etc.  And if that
> adds type-checking, all the better.

In that case, do

local arr
arr=()

wherever necessary.  Now it even looks more like perl :-).  But
type-checking's a bit of chimera here:  there are many cases where
zsh will silently store a scalar into arr.  It does get the behaviour
of a subsequent 'arr[1]=foo' right, however: for example,

% unset arr
% arr[1]=foo arr[2]=foo
% print $arr
foo foo
% unset arr
% local arr
% arr[1]=foo arr[2]=foo
% print $arr
ffooo

In the first case it guesses it has to be an array, in the second it's
already been created as a scalar.  I suppose that's more or less what
you're worried about, in which case I recommend what I wrote above:  I
sometimes do that myself.

-- 
Peter Stephenson <pws@ibmth.df.unipi.it>       Tel: +39 050 844536
WWW:  http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56127 Pisa, Italy

Re: local arrays

[Phil Pennock]

Typing away merrily, Bart Schaefer produced the immortal words:
> On Jan 13, 10:12am, Phil Pennock wrote:
> } Is there a way in zsh-3.0.5 (or zsh-3.1.x) to use one command to declare
> } a variable to be both local and an array?
> 
> No, there isn't.  This is even documented, poorly (a bit better in pws-4,
> because it was part of my rewrite of the `typeset' documentation).
> 
> Why do you need to do this?  The variable will assume array-ness upon the
> first array assignment to it.

Cleanliness.  Obviousness of purpose.

The scripts I write are liable to be modified by others.  So the purpose
of stuff should be clear.  Nice clean explicit statements of what a
variable is help.  So integers get declared as such, etc.  And if that
adds type-checking, all the better.

I just prefer zsh to perl ...
-- 
--> Phil Pennock ; GAT d- s+:+ a23 C++(++++) UL++++/I+++/S+++/H+ P++@ L+++
E-@ W(+) N>++ o !K w--- O>+ M V !PS PE Y+ PGP+ t-- 5++ X+ R !tv b++>+++ DI+ D+
G+ e+ h* r y?

Re: Local arrays

[Peter Stephenson]

On Wed, 06 Feb 2013 17:41:08 +0200
Atte Peltom채ki <atte.peltomaki@iki.fi> wrote:
> Can someone explain the following behaviour in declaring local arrays?

It's actually simpler than you suppose: you can't declare local arrays
in one go.  An expresion like:

local -a foo=(one two three)

isn't an array assignment, because arguments to local are just like any
argument to any other command (to a first approximation).  It's a
declaration with the argument "foo=(one two three)".  Normally in zsh
that parenthesised expression at the end looks like a set of glob
qualifiers, i.e. a bit like "*(.)" or something like that.  That's the
"unknown file attribute" error.

You need to split this up:

local -a foo
foo=(one two three)


pws

Local arrays

[Atte Peltomäki]

Hi,

Can someone explain the following behaviour in declaring local arrays?

% F () { local -a foo=(one two three); echo $foo ; }
% F
F: unknown file attribute

% F () { local foo=(one two); echo $foo ; }
% F
F: missing end of string

% F () { local foo=(moi hei); echo $foo ; }
% F
F: number expected

% F () { local -a foo; foo=(one two three); echo $foo ; }
% F
one two three

% echo $ZSH_VERSION
4.3.17

-- 
Atte Peltomäki
     atte.peltomaki@iki.fi <> http://kameli.org
"Your effort to remain what you are is what limits you"