Re9: Learning how to use the Error module by example

[dragonchild]

sub find {
    my ($self, $search_item) = @_;
    eval {
        # skip expensive search if item not stored anywhere
        throw Signal::Search::Not_Stored
           unless $search_item->stored;

        # otherwise do expensive search
        $self->first;
        while (my $item = $self->next) {
            throw Signal::Search::Found
                if $item == $search_item;
        };
        throw Signal::Search::Not_Found;
    }; if ($@) {
        my $e = $@;

        # Do NOT handle Signals here. Those propagate back
        # up to the caller who will handle them appropriately.
        throw $e if $e->isa('Signal::Search');

        ... handle exceptions here ...
    };
};

I would argue that you have three possible return codes - NOT_STORED, FOUND, NOT_FOUND, plus all the possible exceptions that can occur. Instead of trying to shoehorn your return codes into a C-like morass of constants and bit-vectors, use signalling exceptions! Heck, you can even include a reference to the found item in your Signal::Search::Found object, if you were so inclined. And, your code is self-commenting because you make a distinction between NOT_STORED and NOT_FOUND, in case the caller or reader cares. If they don't, they can explicitly treat the two cases the same, increasing the commenting.

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Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.