As I like to use descriptive parameter names, I often tried to use variable names already used by Zsh itself.
As it took me into trouble in the past, I now wrap my script in a main function named after the script. Then I declare all my local parameter using the local keyword.
But some parameters seems to not allow hiding them in the local scope:
function foo
{
local commands=(bar baz)
local status=0
echo ${(F)commands}
echo $status
}
Here, the local commands parameter is used in place of the special one.
But as the status parameter is read-only, I got the following error:
zdm:6: read-only variable: status
I think that the local keyword allow to use a special parameter in a local scope but it does not change the way it was declared.
To use a special parameter name within a local scope, you have to hide it explicitly using the -h flag of the typeset builtin:
typeset -h status
As you want to declare it as local, use the local keyword which also supports that flag:
local -h status
You can also use the private keyword from the zsh/param/private module:
zmodload zsh/param/private
private -h status
-h flagFrom the Zsh manual:
-hHide: only useful for special parameters (those marked
<S>in the table in Parameters Set By The Shell), and for local parameters with the same name as a special parameter, though harmless for others.A special parameter with this attribute will not retain its special effect when made local. Thus after
typeset -h PATH, a function containingtypeset PATHwill create an ordinary local parameter without the usual behaviour of PATH.Alternatively, the local parameter may itself be given this attribute; hence inside a function
typeset -h PATHcreates an ordinary local parameter and the special PATH parameter is not altered in any way.It is also possible to create a local parameter using
typeset +h special, where the local copy of special will retain its special properties regardless of having the -h attribute.Global special parameters loaded from shell modules (currently those in zsh/mapfile and zsh/parameter) are automatically given the
-hattribute to avoid name clashes.
For a more understandable explanation, see the Zsh manual page about the local parameters.
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