my %opts = (
  # %known_opts enumerates allowed opts as well as specifies default
  #   and initial values
  my %known_opts = (
     'debug' => 0,
     'verbose' => 1,
     'log' => 'log.txt', # default value
     'file' => '',       # actually like declaration of option
  ),
  #options itself
  my %specified_opts = (
    (map {/^--([\-_\w]+)=(.*)$/} @ARGV),      # --opt=smth
    (map {/^no-?(.*)$/i?($1=>0):($_=>1)} map {/^--([\-_\w]+)$/} @ARGV),  # --opt --no-opt --noopt
  ),
);
die "option '$_' is not recognized" for grep {!exists $known_opts{$_}} keys %specified_opts;
@ARGV = grep {!/^--/} @ARGV;
# then normal program goes here