Yet Another CPAN Grep

Log-Any-App ( P/PE/PERLANCAR/Log-Any-App-0.540.tar.gz, PERLANCAR, 2019; MetaCPAN )

Log-Any-App/lib/Log/Any/App.pm ( view source; MetaCPAN )

   }
    $def;
}

# j=as json (except the last default)
sub _ifdefj {
    require JSON::MaybeXS;

    my $def = pop @_;
    for (@_) {
        return JSON::MaybeXS::decode_json($_) if defined($_);

utside the script using environment variable,
which is more flexible. Encode data structure using JSON:

 % LOG_SHOW_CATEGORY=1 \
   LOG_CATEGORY_ALIAS='{"-noisy":["Foo","Bar::Baz","Quz"]}' \
   LOG_C

file for short, previously "flag file") will be searched
in <PROG>.log_options. Its content is in JSON and will become init() arguments.
For example:

 {"file": 1, "screen":{"level":"trace"}}

or more