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Classes Considered Harmful [pdf]

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Re: Classes Considered Harmful [pdf]

#21

Post by marcosdumay »

macintux wrote: post #8

Most eye-opening moment in my software engineering class was when the professor asked, of four core OO features (don't recall the precise list now), which was superfluous. The answer, of course, was inheritance, and once the question was asked it wasn't hard to see how much better life could be without it. I've been on an anti-inheritance kick ever since. Now I see how much better life can be without OO entirely, but…

What do you use to implement interfaces then?

Generic interfaces are the one single feature that made OO popular for GUI programming; what by its turn is the one application that made OO popular. And it's still the most powerful of the OO concepts (what is shame really).

Re: Classes Considered Harmful [pdf]

#22

Post by asavinov »

I like this kind of critical papers but I cannot agree with the author in this case. I have studied this problem quite deeply while working on concept-oriented programming and concept-oriented data model (http://conceptoriented.org/) for many years by also trying to minimize the number of basic constructs. Yet, my conclusion is that classes are actually needed.

There are several major reasons for that. One of them is that we actually need two different relations: 1) membership relation, and 2) inheritance (or inclusion in more general case). Unfortunately, we cannot reduce them to one relation. If we do (in prototype-based languages) then normally we will still distinguish the role of this one relation depending on the context.

Mathematically, we have the membership relation '∈' between an element and a set, and we have the subset relation '⊆'. Just as we need both of them, we need both class instances and classes. In other words, if somebody argues that classes are not needed, then it is analogous to the statement that sets are not needed and it is enough to have only membership relation among elements. It is possible to develop such a theory but then we will get an alternative mathematics. Or we will implicitly treat some elements as sets.

Re: Classes Considered Harmful [pdf]

#25

Post by crbelaus »

Declanomous wrote: post #11
ravenstine wrote: post #4

There seems to be a common fixation on objects "modeling the real world" with the counter argument for classes being that they don't model the real world. True, there isn't a physical chair class in real life(philosophically, there aren't even chairs), but there is a common abstract idea of what would describe the function and attributes of a chair. Granted, it differs a little from person to person, but objects them…

Plato would argue that there is such a thing as a chair. In fact, he'd argue there is an ideal of a chair which all chairs strive to achieve. The idea of Platonic Form (and the allegory of the cave) are very relevant to programming because western philosophy has shaped how we view the world, and thus how we program. That being said, I don't think most people I know are familiar with platonic forms, or the allegory of…

Thank you very much for mentioning Plato here. I was thinking exactly about this wile reading this paragraph:

> Let us also be clear that classes do not “model the real world”. Objects may or may not model the real world, but classes certainly don’t. Although there are many chairs in the real world, there is no “chair class” in the real world.

Re: Classes Considered Harmful [pdf]

#26

Post by eternalban »

asavinov wrote: post #22

I like this kind of critical papers but I cannot agree with the author in this case. I have studied this problem quite deeply while working on concept-oriented programming and concept-oriented data model ( http://conceptoriented.org/ ) for many years by also trying to minimize the number of basic constructs. Yet, my conclusion is that classes are actually needed. There are several major reasons for that. One of them…

http://conceptoriented.org/savinov/publicat/arxiv_1501_00720...

Just skimmed the 'Cross-Cutting Concerns' in your paper above. Isn't AOP far more general than what you propose there? Please correct any misunderstanding but per the parent based approach you describe -- "cross-cutting concerns are modularized in parent incoming methods and this functionality is injected in child methods" -- you would need to duplicate a CCC e.g. logging in each distinct 'parent'.

Re: Classes Considered Harmful [pdf]

#27

Post by lgas »

leblancfg wrote: post #6

Although he spends quite some time on exploring the alternatives, the only reason the author specifically states where classes are harmful is because they are premature optimization . That's it? I guess "Classes considered a PITA" just didn't make a good title.

He delegates to his other paper with "A long discussion of the issues can be found in my submission to MASPEGHI 2013 [1]". That paper can be found here:

http://www.cs.jyu.fi/maspeghi2013/papers.html

specifically:

http://www.cs.jyu.fi/maspeghi2013/p17-black.pdf

Re: Classes Considered Harmful [pdf]

#28

Post by contingencies »

asavinov wrote: post #22

I like this kind of critical papers but I cannot agree with the author in this case. I have studied this problem quite deeply while working on concept-oriented programming and concept-oriented data model ( http://conceptoriented.org/ ) for many years by also trying to minimize the number of basic constructs. Yet, my conclusion is that classes are actually needed. There are several major reasons for that. One of them…

we actually need two different relations: 1) membership relation, and 2) inheritance (or inclusion in more general case).

No. You don't need OO at all, let alone bolt-on conceptual baggage like this.

The notion of object oriented programming is completely misunderstood. It's not about objects and classes, it's all about messages. - Alan Kay[0]

[0] From my fortune clone @ https://github.com/globalcitizen/taoup

Re: Classes Considered Harmful [pdf]

#29

Post by pottereric »

asavinov wrote: post #22

I like this kind of critical papers but I cannot agree with the author in this case. I have studied this problem quite deeply while working on concept-oriented programming and concept-oriented data model ( http://conceptoriented.org/ ) for many years by also trying to minimize the number of basic constructs. Yet, my conclusion is that classes are actually needed. There are several major reasons for that. One of them…

I agree with you in that I don't agree with the author. I felt that the strongest point of the paper was that it was critical of something that is assumed to be a good thing. That value was that it challenged one of my assumptions that I had never questioned.
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