Default true boolean zstyle

Default true boolean zstyle

[Sebastian Gniazdowski]

Hello,
following code explains:

% zstyle -b ":test-context" test_var test_var || test_var="yes"
% echo $test_var
yes
% zstyle ":test-context" test_var 0
% zstyle -b ":test-context" test_var test_var || test_var="yes"
% echo $test_var
yes

Apparently, zstyle -b returns false when the boolean being read is
false. So "|| test_var=yes" is triggered, and the value is
overwritten. Following way also doesn't do what's expected:

% test_var="yes"
% zstyle -b ":test-context" test_var test_var
% echo $test_var
no

Is there a way to have default-true boolean with zstyle?

Best regards,
Sebastian Gniazdowski

Re: Default true boolean zstyle

[Bart Schaefer]

On Thu, Oct 13, 2016 at 11:27 PM, Sebastian Gniazdowski
<sgniazdowski@gmail.com> wrote:
>
> Apparently, zstyle -b returns false when the boolean being read is
> false.
>
> Is there a way to have default-true boolean with zstyle?

You have to use
    zstyle -T :test-context test-style && test_var=yes || zstyle -b
:test-context test-style test_var

Re: Default true boolean zstyle

[Daniel Shahaf]

Bart Schaefer wrote on Fri, Oct 14, 2016 at 10:53:01 -0700:
> On Thu, Oct 13, 2016 at 11:27 PM, Sebastian Gniazdowski
> <sgniazdowski@gmail.com> wrote:
> >
> > Apparently, zstyle -b returns false when the boolean being read is
> > false.
> >
> > Is there a way to have default-true boolean with zstyle?
> 
> You have to use
>     zstyle -T :test-context test-style && test_var=yes || zstyle -b
> :test-context test-style test_var

It's still surprising (and undocumented) that -b returns false when the
value of the style is false.  I expected it to return 0 for the same
reason that _call_function returns 0 when the called function returns
non-zero: $? == 0 means retrieving the value succeeded; check $test_var
to see what the value is.

But it's been this way for 15+ years...