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Re: Checking for Presence of Optional Attribute in Moose Object

by FalseVinylShrub (Chaplain)
on Jul 04, 2010 at 04:41 UTC ( #847954=note: print w/replies, xml ) Need Help??

in reply to Checking for Presence of Optional Attribute in Moose Object


I think your test should work without the warning if you use if (defined $self->age) { ... }.

According to Moose::Manual::Attributes, you could also set up a predicate for that attribute:

has 'age' => ( is => 'ro', isa => 'Str', predicate => 'has_age' ); if ($self->has_age) { ... }

The predicate allows you to have undefined or false values and still know whether it's ever been set or not.

On the other hand, if you just want to be able to interpolate an empty value into a string without warnings, how about putting a default of '':

has 'age' => ( is => 'ro', isa => 'Str', default => '', );

Assumes that '' is not a valid age... But that sounds like a reasonable assumption.


Disclaimer: Please review and test code, and use at your own risk... If I answer a question, I would like to hear if and how you solved your problem.

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[james28909]: Good morning!
[james28909]: I have a problem I am trying to solve. I am packaging scripts using pdk and would like the verify the executable name each time it is executed
[Corion]: Hi James!
[james28909]: I looked through the docs, and see that PerlApp::exe() is suppose to return this information but whenever i try to use this, i get the error "Undefined subroutine &PerlApp::exe called"
[james28909]: i just want to verify the integrity of the executables name each time it is run.

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