I had reason to use the perl functionality built into a vendors software package today. The package comes with 5.8.3, and it's own set of perl modules to do software related tasks like tweaking data records.

At one point, I have to figure out why this didn't work: 

    $valobj->value = undef;

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but this did: 

    $valobj->value = '';

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After looking into the source code, the object and it's methods use the :lvalue attribute. 

    sub value : lvalue {
        my $this = shift;
        $this->{VALUE};
    }

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So, that doesn't work if lvalue is undef, but does work if lvalue is an empty string. Is that a 'feature' of the lvalue attribute, or something about the method?

I wouldn't expect this traditional setup to work: 

    sub value {
        my ($self, $value) = @_;
        if (defined $value) {
            $self->{value} = $value;
        };
    };
    $valobj->value(undef);

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But I would've expected all the work behind :lvalue to fix that.

Updated: Yes, I've read the pod. It's experimental. Good thing they're using it. The pod doesn't really mention what would happen in the case of setting undef though.

-=Chris

In reply to :lvalue, How I Hate Thee by jk2addict

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