package bitflags;

use strict;
my $i = .5;

sub import {
  my $self = shift;
  my $caller = (caller)[0];

  if ($_[0] =~ /^:start=(\^?)(\d+)$/) {
    if ($1) { $i = 2 ** ($2-1) }
    elsif ($2 & ($2 - 1)) {
      require Carp;
      Carp::croak("$2 is not a power of two");
    }
    else { $i = $2/2 }
    shift;
  }

  no strict 'refs';
  for (@_) {
    my $j = ($i *= 2);
    *{"${caller}::$_"} = sub () { $j };
  }
}

1;