Re: [gentoo-dev] Re: use_echo() as a universal '?:' operator-like function

[Francesco R]

2010/9/11 "Paweł Hajdan, Jr." <phajdan.jr@g.o>

> On 9/11/10 11:03 AM, Jonathan Callen wrote:
> > Just as a proof-of-concept, here's one implementation of such a
> > function, allowing for an arbitrary number of arguments:
> >
> > use_echo() {
> >       while [[ $# -gt 1 ]]; do
> >               if use "$1"; then
> >                       echo "$2"
> >                       return
> >               fi
> >               shift 2
> >       done
> >       [[ $# -eq 1 ]] && echo "$1"
> > }
>
> Looks good to me. If it doesn't get included in any eclass, I will just
> paste it to the chromium ebuilds. :)
>
> Paweł
>
> I don't count but sometimes I do still read ebuilds, the function proposed
look a bit^W unreadable to me,
may I suggest to aggregate use and echo, separating them with a comma ",".
The first element with an empty "use" always echo and return.

See implementation and example below

use_case() {
        local u
        local c
        while [[ $# -gt 0 ]]
        do
                u=${1%%,*}
                c=${1#*,}
                if [[ ${u} == "" ]] || use $u
                then
                        echo ${c}
                        break
                fi
                shift
        done
}

echo $(use_case useA,echoA useB,echoB ,echoC)