fixed warnings

[forwardever]

I got this mail from the author of Devel::TrackObjects regarding strange warnings:

Hi,

$tracked->[0] is the object itself.

If you print it it will stringify it. Stringification is overloaded
in Date::Time using Date::Time::_stringify, which will use ymd and hms
to stringify the object.

If the Date::Time object itself contains no $self->{local_c} yet the
values for sprintf in ymd and hms will be undef which causes the
warnings.

So this is not really a bug in DateTime, because they never intended
for somebody to stringify some internal objects. But it's not a bug
in Devel::TrackObjects either.
Let's just say, they are not made to work close together.

But I've worked now around this overloading when debugging is enabled
(just released 0.5, see https://github.com/noxxi/p5-devel-trackobjects)
and so can you:

+ use overload;
...
-      warn $tracked->[0];
+      warn overload::StrVal($tracked->[0]);

[miyagawa]

This issues misses the context - What is the original problem you had?

[forwardever]

I have created a simple test case, so the following code produces lots of warnings, or when it comes to plack middleware debug, I get a bunch of warnings with every request in my console window:

warning:
Use of uninitialized value in sprintf at C:/strawberry/perl/site/lib/DateTime.pm line 766

test case:

sub import {
    use Devel::TrackObjects qr/^/;
}

use DateTime;

my $dt = DateTime->now;
$dt->set_time_zone('UTC');
$dt->set_time_zone('Europe/Paris');
print "Hello World";

my $tracked = Devel::TrackObjects->show_tracked_detailed;

foreach my $tracked (@$tracked) {
    warn $tracked->[0];
}

which is fixed by

use overload;

sub import {
    use Devel::TrackObjects qr/^/;
}

use DateTime;

my $dt = DateTime->now;
$dt->set_time_zone('UTC');
$dt->set_time_zone('Europe/Paris');
print "Hello World";

my $tracked = Devel::TrackObjects->show_tracked_detailed;

foreach my $tracked (@$tracked) {
    warn overload::StrVal($tracked->[0]);
}