http://www.perlmonks.org?node_id=230051


in reply to Re: Unblessed Reference Message
in thread Unblessed Reference Message

A ref becomes an object after being blessed, as now Perl knows who/what it is.

This is incorrect, and will eventually bite you in the rear end. From perlfunc: 

       bless REF,CLASSNAME
       bless REF
               This function tells the thingy referenced by
               REF that it is now an object in the CLASSNAME
               package...

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It is the thing referred to, not the reference, that is blessed. This is why we can copy the reference returned by bless and still invoke methods against the reference--perl knows that the reference refers to an object of class class because it's the referent that is marked as belonging to a particular package.

In Section Seekers of Perl Wisdom