I've run into some strange behavior when passing objects around in Perl 5.6.1 I'm writing a class ("Emitter") that represents a hidden state in a hidden markov model. An Emitter instance contains a transition table, which contains other Emitter instances. The idea is to have a transition method so that calling $emitter->transition() returns the next Emitter in the Markov chain. The problem is that running : 
$next_emitter = $current_emitter->transition();
print $next_emitter->emit() . "\n";

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results in 
Can't locate object method "emit" via package
"Emitter=HASH(0x1016c9c0)" (perhaps you forgot to load
"Emitter=HASH(0x1016c9c0)"?) at HMM/ODCRollGenerator.pm line
100.

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Indeed, 
ref($an_emitter->transition());

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results in Emitter=HASH(0x1016c9c0) whereas 
ref($an_emitter)

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gives Emitter as expected.

Within an Emitter, the transition table is stored as a hash, with the other Emitter instances as the keys, and the transition probabilities as the values. i.e. the setter method looks like this: 

sub transitions
{
    my $self = shift;
    if (@_)
    {
        $self->{TRANSITIONS} = shift;
        &_build_prob_table($self);
    }
    return $self->{TRANSITIONS};
}

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and it might be called like this: 
$self->{START} = Emitter->new();
$self->{FAIR} = Emitter->new();
$self->{LOADED} = Emitter->new();
...
$self->{START}->transitions( { $self->{FAIR} => 0.5,
                               $self->{LOADED} => 0.5 } );

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Now, I can make things work by re-blessing the reference returned by transition(), but this seems awfully kludgy, and I suspect there is a better way to do this. Besides, as I understand it, it's the underlying thingy, not the reference, that is blessed. Anyone know what's going on here? Is there some magic I need to add to the class to keep the blessing attached to objects?

In reply to objects becoming unblessed? by omnibus

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