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Re^11: OO automatic accessor generation

by stvn (Monsignor)
on Nov 13, 2009 at 19:05 UTC ( #807028=note: print w/ replies, xml ) Need Help??


in reply to Re^10: OO automatic accessor generation
in thread OO automatic accessor generation

FatOldMonk++

Seriously though, it could be argued that sending people to learn the old, tedious way of Perl OOP first will drive some new users away. Especially with languages like Ruby and Python out there which have nice OO out of the box. Don't get me wrong, I totally think that you should learn your roots, but Perl OOP not only imposes a lot more work but can teach really wrong headed behavior (due largely to its extreme minimalism), just look at like the last 2/3rds of Damians OO book, it is full of overly clever tricks that should never be done in the real world. At some point people just need to get work done.

-stvn


Comment on Re^11: OO automatic accessor generation
Re^12: OO automatic accessor generation
by Anonymous Monk on Nov 13, 2009 at 20:57 UTC
    just look at like the last 2/3rds of Damians OO book, it is full of overly clever tricks that should never be done in the real world. At some point people just need to get work done.

    Maybe it's been a while since you actually read Damian's OO book, because that's not how it seems to me.

    Of the 14 chapters, the first two give good general introductions to the concepts of OO and the bits of Perl you need to understand to understand OO Perl. The nest five explain the basic way Perl OO works (though Chapter 5--on blessing non-hashes--has a lot of stuff that most developers would never need). Chapter 8 explains two outdated approaches to class creation (i.e. earlier and more easily understood versions of what Moose does now). Chapter 9 explains ties (which certainly are overly clever). Chapter 10 looks at operator overloading (and the last third of the chapter actually counsels against clever tricks). Chapter 11 covers several outdated approaches to encapsulation (which I know you don't consider important, but some of us do). Chapter 12 works through a simple example of polymorphic design. Chapter 13 looks at multiple dispatch (a "trick" so useful that it's now fundamental to, and used everywhere in, Perl 6). The final chapter shows a whole lot of definitely overly clever tricks for creating object persistence mechanisms.

    So there are clearly "overly clever tricks" in chapters 9 and 14, and arguably some in parts of chapters 5, 11, and 13. By my count that's about 100 pages out of 490, or around 20%. Instead of 2/3 of the book being wrong-headed, it seems to me that the first 40% of it is an good solid introduction to the way OO Perl actually works; and that most of the rest of consists of useful, but non-essential, explanation too. Not bad for a book written a decade ago.

    Personally, I'd rather have developers who have read Damian's OO book and therefore understand the underlying Perl OO mechanisms that Moose uses (or sometimes replaces), than have developers who don't understand how Perl OO actually works and just treat Moose as a magic wand.

      So by your count out of 14 chapters six document outdated or overly tricky features of the Perl OO model (5,8,9,10,11,14). while Five are straight forward useful (1,2,3,4,12) ... and one is useful but advanced (13).

      By my count that's 35% of the chapters that are directly useful to a Perl5 developer today. Those chapters are also front-loaded. Not bad for a flippant remark.

      As for encapsulation, I've listened to stvn's rant about it more than most people. The point isn't that encapsulation is bad, the point is that going out of your way to enforce encapsulation in a language like Perl is simply adding complexity with no benefit. Why double your code when a simple rolled up news paper across the nose is sufficient? "Bad Programmer, No Cookie!"

      That said I'd agree with you, I'd rather have a developer who read Damian's OO book for the 1/3 that is *useful* about OO Theory ... and then used Moose ... rather than a developer that doesn't understand OO at all and things Moose is a Magic Bullet. But given a raw programmer, I'd rather have them learn good OO theory using a proper tool like Moose than I would have to re-teach them all the things I had to forget when I moved from raw Perl OO to Moose three years ago.

        So by your count out of 14 chapters six document outdated or overly tricky features of the Perl OO model (5,8,9,10,11,14). while Five are straight forward useful (1,2,3,4,12) ... and one is useful but advanced (13).
        No. By my count, the vast majority of about ten chapters is still directly useful.
        By my count that's 35% of the chapters that are directly useful to a Perl5 developer today
        By my count, it's 70% still useful. Just because you don't choose to implement a design using Class::MethodMaker, doesn't make learning it useless. Likewise, encapsulation and multiple dispatch. I despair when people think that only the stuff they'll need today is useful. Knowing how others have done things in the past is valuable. Breadth of understanding is worthwhile, even if you never use the techniques shown yourself.

        I've heard Damian Conway call that "repertoire" and say how important it is to know a wide range of things, both fundamental and advanced, useful and "tricky". He says it's one of the things that makes a good programmer a great programmer, not just because you know five ways to solve a problem, but also because understanding five ways and their advantages and limitation helps you see why one particular way is better than the other four.

        Besides, basing that "flippant remark" on a chapter count (however you choose to count them) is utterly misleading. It assumes all chapters are equally long, which they're certainly not. Might as well say that 1 out of 1 "OO Perl" books contain invalid material, so the book's 100% invalid. Or that 207 of the 283 Moose:: modules have at least open bug report, so Moose is 73% buggy.

        In fairness, not all pages are equal either, so basing any evaluation of the book on page counts is misleading too. But at least there are enough pages for the differences to even out, so page counts get nearer the truth than basing an assessment on arbitrary divisions like chapters.

        The point isn't that encapsulation is bad, the point is that going out of your way to enforce encapsulation in a language like Perl is simply adding complexity with no benefit. Why double your code when a simple rolled up news paper across the nose is sufficient? "Bad Programmer, No Cookie!"
        There's no point arguing this. You could argue exactly the same about (for example) Moose bringing type checking to attribute assignments.

        Encapsulation does bring benefits, and can certainly be added to Perl without "doubling the code". Modern inside-out techniques are hardly any more onerous than vanilla hash-based objects, and modules like Object::InsideOut make simple encapsulated classes even less onerous to set up than using Moose.

        But given a raw programmer, I'd rather have them learn good OO theory using a proper tool like Moose than I would have to re-teach them all the things I had to forget when I moved from raw Perl OO to Moose three years ago.
        You know, it's always respected programmers like yourself who I see advising us beginners to avoid learning all the core stuff that made you excellent programmers excellent in the first place. Knowing how OO Perl actually works, you have the luxury of wishing you didn't, while still enjoying the many subtle benefits of that knowledge. It's almost like a conspiracy by the Perl elite to keep the masses in our proper state of limited understanding. ;-)

        Seriously though, understanding how things actually work is important, even when very useful coatings of module-based magic are layered over them. You can't really be great at a language if you don't understand how that language really works, no matter how well you understand any tool built on top of that language. Ultimately, all metaphors break down, and that's just as true of the programming metaphors we call libraries or modules. And, at that point, if you don't understand the mechanism the metaphor is simplifying, you're in deep trouble.

        I guess my point is that throw-away remarks that denigrate a dated but well-written book (which still contains, in my view, a lot more than just 1/3 useful information) don't really do justice to the book, to Moose, or to Perl. Or to the many beginners who want to benefit from understanding all three.

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