[Devel::Cover] Missed Coverage

[David Wheeler]

Hi Paul et al.,
In an iterator class I've written, I have this method:
sub do {
    my ($self, $code) = @_;
    while (local $_ = $self->next) {
        return unless $code->($_);
    }
}
I've written tests for when the code reference returns true and when it  
returns false. However, Devel::Cover can't tell. It thinks I've missed  
the C<unless $code->($_)> part.

   
http://dev.kineticode.com/bricolage2/coverage/blib-lib-Bricolage-Util- 
Iterator-pm--branch.html

Only if I change the method to this:
sub do {
    my ($self, $code) = @_;
    while (local $_ = $self->next) {
        my $ret = $code->($_);
        return unless $ret;
    }
}
can Devel::Cover tell that the unless expression is covered. Since I  
don't want to really create an extra variable to store and check a  
value just to make Devel::Cover see it, is there a way that  
Devel::Cover could learn to see it, or that I could assure Devel::Cover  
that, yes, it really is covered?

Thanks!
David