On Thu Oct 04 16:42:23 2012, BUBAFLUB wrote:
Show quoted text> Hello,
>
> Devel::Cover defines $DB::single and sets it to 0. Example:
>
> running:
>
> perl -e 'print "\$DB::single is: " . $DB::single'
>
> outputs:
>
> $DB::single is:
>
> ($DB::single is undefined)
>
> while running with Devel::Cover:
>
> perl -MDevel::Cover -e 'print "\$DB::single is: " . $DB::single'
>
> prints (among the other Devel::Cover related output):
>
> $DB::single is: 0
>
> I was unable to find anywhere in the code where this was explicitly
> set. It's possible it was
> done by a module that Devel::Cover uses.
My hunch is that this is a problem which manifests itself only when Devel::Cover is used with a command-line program that does not exercise a file.
First, I run a program at the command-line very similar to yours:
##########
$ perl -w -MDevel::Cover -E 'say "\$DB::single is: <$DB::single>"'
Devel::Cover: Can't find file "-e" (-e): ignored.
Devel::Cover 1.00: Collecting coverage data for branch, condition, pod, statement, subroutine and time.
Selecting packages matching:
Ignoring packages matching:
/Devel/Cover[./]
Ignoring packages in:
/usr/local/lib/perl5/site_perl/5.16.0/darwin-2level
/usr/local/lib/perl5/site_perl/5.16.0
/usr/local/lib/perl5/5.16.0/darwin-2level
/usr/local/lib/perl5/5.16.0
/usr/local/lib/perl5/site_perl/5.14.2
/usr/local/lib/perl5/site_perl/5.14.0
/usr/local/lib/perl5/site_perl/5.12.0
/usr/local/lib/perl5/site_perl/5.10.1
/usr/local/lib/perl5/site_perl/5.10.0
/usr/local/lib/perl5/site_perl
$DB::single is: <0>
Devel::Cover: Writing coverage database to /Users/jimk/Documents/AAAPerl/Devel-Cover/80340/cover_db/runs/1365767158.479.13352
---------------------------- ------ ------ ------ ------ ------ ------ ------
File stmt bran cond sub pod time total
---------------------------- ------ ------ ------ ------ ------ ------ ------
Total n/a n/a n/a n/a n/a n/a n/a
---------------------------- ------ ------ ------ ------ ------ ------ ------
##########
Note that Devel::Cover appears to be expecting to find a file, cannot do so, and throws out a warning. That's not entirely surprising, because there are no statements to be exercised.
Later in the output, $DB::single is set to 0, as you reported.
Now, I take a program found in another bug ticket in this rt.cpan.org queue and modify it by sticking in this one line just before the file exits:
##########
$ cat 80340_simple.pl
#!/usr/bin/perl
use strict;
use Test::More 'no_plan';
my @x = ('a'..'c');
my $foo;
my $n = 0;
foreach (@x) {
$foo .= $_;
} continue {
$n++;
}
is $foo, 'abc';
is $n, 3;
print STDERR '$DB::Single: ', $DB::Single, "\n";
__END__
##########
When I run this *without* Devel::Cover, it reports $DB::Single as undefined:
##########
$ perl -w 80340_simple.pl
Name "DB::Single" used only once: possible typo at 80340_simple.pl line 19.
ok 1
ok 2
$DB::Single: Use of uninitialized value $DB::Single in print at 80340_simple.pl line 19.
1..2
##########
Next, I run the same program *with* Devel::Cover:
##########
$ perl -w -MDevel::Cover 80340_simple.pl
Name "DB::Single" used only once: possible typo at 80340_simple.pl line 19.
Devel::Cover 1.00: Collecting coverage data for branch, condition, pod, statement, subroutine and time.
Selecting packages matching:
Ignoring packages matching:
/Devel/Cover[./]
Ignoring packages in:
/usr/local/lib/perl5/site_perl/5.16.0/darwin-2level
/usr/local/lib/perl5/site_perl/5.16.0
/usr/local/lib/perl5/5.16.0/darwin-2level
/usr/local/lib/perl5/5.16.0
/usr/local/lib/perl5/site_perl/5.14.2
/usr/local/lib/perl5/site_perl/5.14.0
/usr/local/lib/perl5/site_perl/5.12.0
/usr/local/lib/perl5/site_perl/5.10.1
/usr/local/lib/perl5/site_perl/5.10.0
/usr/local/lib/perl5/site_perl
ok 1
ok 2
$DB::Single: Use of uninitialized value $DB::Single in print at 80340_simple.pl line 19.
1..2
Devel::Cover: Writing coverage database to /Users/jimk/Documents/AAAPerl/Devel-Cover/80340/cover_db/runs/1365767843.492.61503
---------------------------- ------ ------ ------ ------ ------ ------ ------
File stmt bran cond sub pod time total
---------------------------- ------ ------ ------ ------ ------ ------ ------
80340_simple.pl 100.0 n/a n/a 100.0 n/a 100.0 100.0
Total 100.0 n/a n/a 100.0 n/a 100.0 100.0
---------------------------- ------ ------ ------ ------ ------ ------ ------
##########
It *still* reports $DB::Single as undefined. So when you use Devel::Cover as it presumably expects to be used (i.e., with a file), then it does not set $DB::single. When you use Devel::Cover in a way that it does not expect to be used, it sets $DB::single to 0.
I don't think there's any bug here sufficient to warrant changes in Devel::Cover. I recommend that this ticket be closed.
Thank you very much.
Jim Keenan
