呼び出し可能なサブルーチンを限定する

gistfile1.pl

{
    my %foo = (
        start       => 0,
        template    => 0,
        entries     => 0,
        filter      => 1,
        skip        => 1,
        interpolate => 1,
        head        => 1,
        sort        => 1,
        date        => 1,
        story       => 1,
        foot        => 1,
        last        => 1,
        end         => 1,
    );

    sub _foo {
        my $sub = shift;
        $sub =~ s/.*:://o;
        $foo{$sub};
    }
}

sub new {
    my $sub = ( caller(1) )[3];
    croak unless _foo( $sub );
}