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Re^2: Conditional inheritance strategy

by JavaFan (Canon)
on Oct 27, 2010 at 14:31 UTC ( #867737=note: print w/replies, xml ) Need Help??


in reply to Re: Conditional inheritance strategy
in thread Conditional inheritance strategy

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 from new? 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.

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Re^3: Conditional inheritance strategy
by BrowserUk (Pope) on Oct 27, 2010 at 14:52 UTC

    If nothing else, having the initialisation class in the inheritance tree via @ISA, is baggage, if there are no other methods than _init(). Looking back at the OPs code, there seems to be little reason for calling the _init() routines as methods rather than subroutines.

    Indeed, as no instance of the initialisation classes is ever instantiated, it could equally be termed "poor OO". And it is a weird use of "inheritance" in every sense. If the idea is simple to provide two methods of initialisation, better I would say to have them both in the main My package space called (say) _initFromXML() and _initFromJSON() and ditch the extra package spaces entirely.

    But, as I said, it is quite hard to tell from what the OP posted, as he has obviously simplified the code for the purpose of the question. It is always possible that he also has code in each base package to persist the objects to disk or database, which might make all the difference.


    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
      If nothing else, having the initialisation class in the inheritance tree via @ISA, is baggage, if there are no other methods than _init().
      Well, calling two one element arrays "baggage" is stretching the meaning of "baggage". But even so, it's not baggage attached to any instance of the class. Just the classes themselves.
      Looking back at the OPs code, there seems to be little reason for calling the _init() routines as methods rather than subroutines.
      Hmm, yeah, but that seems to be true of at least 95% of OO code written. I'm not the worlds biggest OO fan, but if I were to do something like the OP, I'd use 3 classes as well, with two classes having just an init method (but with the inheritance tree as showed elsewhere in the thread).
      Indeed, as no instance of the initialisation classes is ever instantiated, it could equally be termed "poor OO".
      Really? You only use inheritance if you instantiate every class of your inheritance tree? (Or do you write "poor OO" code?)
      If the idea is simple to provide two methods of initialisation, better I would say to have them both in the main My package space called (say) _initFromXML() and _initFromJSON() and ditch the extra package spaces entirely.
      While certainly possible, it's not something I would do.

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