On Thu, Jul 20, 2023 at 06:58:04PM +0200, Ulrich Mueller wrote:
> >>>>> On Thu, 20 Jul 2023, Mike Gilbert wrote:
> 
> > On Thu, Jul 20, 2023 at 11:06 AM Florian Schmaus <flow@gentoo.org> wrote:
> >> While the bash language has no boolean datatype, you can exploit the
> >> fact that 'true' and 'false' are usually shell builtins:
> >> 
> >> : "${MESON_VERBOSE:=true}"
> >> 
> >> and then later
> >> 
> >> if $MESON_VERBOSE; then
> >> mesoncompileargs+=( --verbose )
> >> fi
> 
> > I think we generally try to avoid exploiting that behavior in ebuilds.
> > It's usually much more obvious to check for a non-empty string, or for
> > a specific value.
> 
> Testing for a non-empty variable is also faster than executing "true"
> or "false" builtins from variable values. (Which doesn't play any role
> here, but readability of the code does.)

Yes, this is what I'd recommend typically. Then documentation can say
"if set to a non-empty value" to toggle.

Unfortunately this doesn't work so great when the default is enabled.
Telling people to empty it is probably weird.

wrt true/false, given MESON_VERBOSE can be set "by users" to anything
I think trying to execute that would be extra weird.

On a side-note, another way to avoid case statements is extglob which
is always enabled in [[ ]] (no need for shopt)

aka: [[ ${var} == @(first|second|third) ]]
-- 
ionen