Re^3: Namespace weirdness with Parallel::ForkManager using 0 children

Adding the following line at the end of sub BUILD in “MyClass.pm” seems to fix the problem:

Role::Tiny->apply_roles_to_object($self, $module);
[download]

So my guess is: roles are, by default, class-based, rather than object-based, so that once a role has been added to a class, the definition of that class doesn’t change. But with multiple threads, the problem doesn’t arise as the class definition is re-created for each new thread.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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Re^4: Namespace weirdness with Parallel::ForkManager using 0 children by 1nickt (Canon) on Mar 21, 2016 at 08:14 UTC
Ha, that's actually what I suspected, that the package was being permanently altered in Perl's brain the first time through. I just didn't think that `with()` operated on the package level, as does `apply_roles_to_package` (which I was eschewing because of that). But it gets back to what I mentioned in an earlier discussion, which is that using `apply_roles_to_object` seems to break the whole point of Roles, in that using it in `sub BUILD` in the parent causes the child's method to be loaded before the parent's of the same name. Notably, placing the conditional code inside an `after BUILD => sub { ... };` block makes no difference to the outcome. `package MyClass; use Moo; use Moo::Role(); sub BUILD { my ( $self, $args ) = @_; my $module = $args->{'num'} % 2 ? 'Odd' : 'Even'; warn "$args->{'num'} $self loading $module"; Moo::Role->apply_roles_to_object( $self, $module); return $self; }; sub baz { return 'qux'; } 1;` [download] And in each of the Roles: `sub baz { die "Died in ", __PACKAGE__; }` [download] Output: `1 MyClass=HASH(0x19c12c0) loading Odd at MyClass.pm line 14. Loaded Odd at Odd.pm line 4. 1 MyClass__WITH__Odd=HASH(0x19c12c0)->bar at test.pl line 11. Died in Odd at Odd.pm line 11.` [download] I guess I will just code around that; indeed I don't reuse method names anywhere as a practise ... but it seems odd. Oh well. ++Athanasius for helping me figure out that I was just seeing another symptom of the same issue I was dealing with earlier! The way forward always starts with a minimal test.	[reply] [d/l] [select]

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Re^4: Namespace weirdness with Parallel::ForkManager using 0 children
by 1nickt (Canon) on Mar 21, 2016 at 08:14 UTC

Ha, that's actually what I suspected, that the package was being permanently altered in Perl's brain the first time through. I just didn't think that with() operated on the package level, as does apply_roles_to_package (which I was eschewing because of that).

But it gets back to what I mentioned in an earlier discussion, which is that using apply_roles_to_object seems to break the whole point of Roles, in that using it in sub BUILD in the parent causes the child's method to be loaded *before* the parent's of the same name. Notably, placing the conditional code inside an after BUILD => sub { ... }; block makes no difference to the outcome.

package MyClass;
use Moo;
use Moo::Role();

sub BUILD {
    my ( $self, $args ) = @_;

    my $module = $args->{'num'} % 2 ? 'Odd' : 'Even';
    warn "$args->{'num'} $self loading $module";

    Moo::Role->apply_roles_to_object( $self, $module);

    return $self;
};

sub baz {
    return 'qux';
}

1;
[download]

sub baz {
    die "Died in ", __PACKAGE__;
}
[download]

1 MyClass=HASH(0x19c12c0) loading Odd at MyClass.pm line 14.
Loaded Odd at Odd.pm line 4.
1 MyClass__WITH__Odd=HASH(0x19c12c0)->bar at test.pl line 11.
Died in Odd at Odd.pm line 11.
[download]

I guess I will just code around that; indeed I don't reuse method names anywhere as a practise ... but it seems odd. Oh well. ++Athanasius for helping me figure out that I was just seeing another symptom of the same issue I was dealing with earlier!

The way forward always starts with a minimal test.

[reply]
[d/l]
[select]