This function implements the interface I described in Re^2: Abritrary multiple spaces as delimiter. You call it like so:

unpack_fields(
    $record,
    \my $num    => 7,
    padding     => 1,
    \my $title  => 27,
    padding     => 1,
    \my $author => 25,
    padding     => 1,
    \my $flag1  => 1,
    padding     => 5,
    \my $flag2  => 1,
);

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I assume this is self explanatory. :)

# this would be much easier in Perl 6

sub unpack_fields {
    my $record = shift;

    my @var;

    my $template = join " ", map {
        my ($field, $width) = splice @_, 0, 2;
        push @var, $field if ref $field;
        ( ref $field ? 'A' : 'x' ) . $width;
    } 0 .. $#_ / 2;

    my @value = unpack $template, $record;

    ${ shift @var } = shift @value while @value;
}

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