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A way to do it is with a predicate.

BEGIN { package Person; use Moose; use overload '""' => sub { +shift->show_person }, fallback => 1; has 'name' => is => 'ro', isa => 'Str', required => 1; has 'age' => is => 'ro', isa => 'Str', predicate => 'has_age'; sub show_person { my $self = shift; join(", ", $self->name, $self->has_age ? $self->age : "age unknown"); } __PACKAGE__->meta->make_immutable; no Moose; 1; } my $person = Person->new({ name => "Bob" }); print $person->show_person, "\n"; print Person->new({ name => "Your Uncle", age => 93 }), "\n";

More here: Moose::Manual::Attributes.

(Update: man! I waited for hours to see if anyone would bite on this and when I finally go to post, FalseVinylShrub hit create while I was typing.)

In reply to Re: Checking for Presence of Optional Attribute in Moose Object by Your Mother
in thread Checking for Presence of Optional Attribute in Moose Object by roho

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