Based upon the above assumption, I would suggest that by using inheritance here, you are loading--and persisting--the overheads of the XML or JSON classes into each instance of My class for no good reason. That is, you are forcing each instance of My class to carry around the baggage--instance data and class references--of whichever base class was used to initialise it. And for no good reason, as that baggage will never be used again during the life of the My class instance.
I wonder what baggage you are referring to. I would presume to point of _init
is to set up instance data - why else call a method named _init
? Of course, if said data is never used, it's pointless, but the code fragment doesn't suggest so. As for a class reference, any object will have a class reference - a single string (package name). The reference doesn't increase depending whether inheritance is used or not. But even if I misunderstood you, your arguments seem to be against using inheritance in general, and not specific to the OP.