Be very careful calling UNIVERSAL::isa as a function, though, and be sure that's what you want. It's nice in that you can throw any reference at it whether or not it's blessed, but it doesn't allow various facade or delegation patterns that don't rely on @ISA inheritance, but do override isa to signal that they do, indeed, subclass an object through other means. This is probably better (using blessed as recommended): 

blessed $obj && $obj->isa('foo')

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-xdg

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In reply to Re^2: How to differentiate hash reference and object reference? by xdg
in thread How to differentiate hash reference and object reference? by tphyahoo

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