Asks dpmott:

How can I make a single reference that can be LEGALLY DEREFERENCED as a hash ref, array ref, AND a scalar ref, with the resulting operation tied to a class implementation?

Probably the easiest thing is to use a glob:

    my $thing;
    { $thing = local *GLOB; }
    $$thing = 20;
    @$thing = (1,2,3);
    %$thing = ('apple'=>'red', 'banana'=>'yellow');
   
    # or use $thing->[...] and $thing->{...}

    # or tie as usual:
    tie %$thing => Hashclass, ...;
    tie @$thing => Arrayclass, ...;
    tie $$thing => Scalarclass, ...;
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The biggest drawback of this approach is that you can't bless the resulting $thing, because it isn't really a reference. But perhaps you don't care to do so.

Hope this helps.

--
Mark Dominus
Perl Paraphernalia