%setting = map {/^--(.*?)=/ => /=(.*)$/} @ARGV;
The first one is the only one I think works well.

It would also work just as well as:

    my %setting = map /^--(.*?)=(.*)$/, @ARGV;
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    %file = map {$_ => (s/^([^=-]*)$/$1/)} @ARGV;
    %switch = map {$_ => (s/^--([^=]*)$/$1/)} @ARGV;
The 2nd one had to go next since the 3rd messes up the arguments for future passes through @ARGV.

Any expression that modifies $_ also modifies @ARGV so both the 2nd and 3rd modify @ARGV.    However, you don't have to modify $_ to get the results that you want:

    my %file = map { $_ => /^([^=-]*)$/ ) } @ARGV;
    my %switch = map { $_ => /^--([^=]*)$/ } @ARGV;
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