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Alan Kay on the Meaning of “Object-Oriented Programming” (2003)

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Re: Alan Kay on the Meaning of “Object-Oriented Programming” (2003)

#51

Post by vishnugupta »

"OOP to me means only messaging, local retention and protection and hiding of state-process, and extreme late-binding of all things. It can be done in Smalltalk and in LISP. There are possibly other systems in which this is possible, but I'm not aware of them."

Such a pity that this filtered essence about OOP was lost on me during formative years of learning OO-programming; for no fault of mine! It took me half a decade into professional programming in Java to realize the importance of these key concepts.

And the worse part is that most of the books/blogs start OO programming tutorial with examples that try to literally model the problem state using Objects (e.g., "Animals", "Shapes" etc.,).

I guess tutorials, classes just focus on these key goals and show how concepts such as "polymorphism", "inheritance" etc., are work towards achieving (or not) them. What generally happens is that one is taught about all these peripheral concepts and students are left to wonder the problems they are trying to solve.

Re: Alan Kay on the Meaning of “Object-Oriented Programming” (2003)

#52

Post by xsmasher »

Joeri wrote: post #16
archagon wrote: post #9

Earlier quoted context omitted.

It seems to me that you can't really do message passing in most languages with high efficiency? (Objective-C and Swift being the exceptions.)

I think it's a bit charitable to call what Objective C does to be "message passing". The messages are not asynchronous and have only a single recipient, so in practice I would say they're method calls with late binding.

At least you can redirect messages to another recipient, and write a handler for "unhandled messages." Impossible with c++, at least with standard method calls.

Re: Alan Kay on the Meaning of “Object-Oriented Programming” (2003)

#53

Post by rumcajz »

robert_tweed wrote: post #2

A lot of the recent trend towards OOP-bashing comes from bad implementations of OOP, just as bashing design patterns is more to do with badly thought out architectures and overuse of those patterns. In fact, the origins of OOP are basically what we would now call microservice architecture (CSP-inspired languages like Go being a specialisation of this). Each service can be as stateless or as stateful as it needs to be…

Alan Kay may have coined the term, but OOP (as any other word or term) is what people believe it to be. Which is pretty far from CSP.

Re: Alan Kay on the Meaning of “Object-Oriented Programming” (2003)

#54

Post by trhway »

robert_tweed wrote: post #2

A lot of the recent trend towards OOP-bashing comes from bad implementations of OOP, just as bashing design patterns is more to do with badly thought out architectures and overuse of those patterns. In fact, the origins of OOP are basically what we would now call microservice architecture (CSP-inspired languages like Go being a specialisation of this). Each service can be as stateless or as stateful as it needs to be…

>A lot of the recent trend towards OOP-bashing comes from bad implementations of OOP, just as bashing design patterns is more to do with badly thought out architectures and overuse of those patterns.

sorry, but this is no true Scotsman fallacy. All these "bad implementations" is OOP, real OOP, not some idealized ephemeral non-existent Avalon. If an idea easily and more frequently than not lands itself to the bad implementations then there is something wrong with the idea. (I happen to come from a country which was pursuing what was looking like a pretty good idea - communism - which has got a lot of bashing during recent decades, due to "bad implementations" i guess, and as result it was critically rethought and now we know what it is not a good idea really)

Re: Alan Kay on the Meaning of “Object-Oriented Programming” (2003)

#55

Post by Jare »

backlava wrote: post #40
Jare wrote: post #22

Earlier quoted context omitted.

Ability to change or replace object instances (maybe with instances of different types) on the fly could be an example. In general, you can design incredibly dynamic and reconfigurable systems. Whether you want to or not, and at what level should you stop doing it, is certainly a good debate to have.

If the system you are building makes sense, there is probably a reasonable type system that shows it to be well typed.

Yeah, "makes sense" and "reasonable" would be criteria involved in the debated I mentioned.

Re: Alan Kay on the Meaning of “Object-Oriented Programming” (2003)

#56

Post by pdubroy »

noblethrasher wrote: post #43
pfraze wrote: post #3

Towards the end: But just to show how stubbornly an idea can hang on, all through the seventies and eighties, there were many people who tried to get by with "Remote Procedure Call" instead of thinking about objects and messages. Sic transit gloria mundi. Can somebody explain to me what distinction he's drawing here? What's the issue with RPC that's solved by Objects+Messages?

In a Smalltalk-style message passing system, each object has its own little parser. When you send it a message, the object will parse and interpret it however it wishes. Essentially, you send the object a sequence of tokens, it parses the tokens and generates some executable code that it then invokes. In C# (or Java), it would look something like this: interface Message : IEnumerable { } public class Foo { public voi…

Sounds more like you're describing Smalltalk 72 (http://worrydream.com/EarlyHistoryOfSmalltalk/#p12) than Smalltalk 80. I've written a fair bit of Smalltalk code, and I can't remember seeing something like what you're describing here. It would certainly be possible, but I don't think it's an accurate description of how most Smalltalk code works.

Re: Alan Kay on the Meaning of “Object-Oriented Programming” (2003)

#57

Post by tim333 »

cesarbs wrote: post #45

> I wanted to get rid of data. What exactly does he mean by that? How does one get rid of data? > The B5000 almost did this via its almost unbelievable HW architecture. I've heard about the B5000 numerous times here on HN. What was so fantastic about it?

http://en.wikipedia.org/wiki/Burroughs_large_systems#B5000

Re: Alan Kay on the Meaning of “Object-Oriented Programming” (2003)

#58

Post by swalsh »

vishnugupta wrote: post #51

"OOP to me means only messaging, local retention and protection and hiding of state-process, and extreme late-binding of all things. It can be done in Smalltalk and in LISP. There are possibly other systems in which this is possible, but I'm not aware of them." Such a pity that this filtered essence about OOP was lost on me during formative years of learning OO-programming; for no fault of mine! It took me half a dec…

Those examples worked really badly for me too. It wasn't until about a year after I got my first paycheck for writing code that I made this switch in my mind. My thought process started out something along the lines of "ok, i just need to get all these things in line... somehow... and then I can accomplish the goal". However at some point I realized, I did some similar things quite often, and I needed to make some piece of code kind of generic. My mindset kind of changed dramatically. Instead of thinking about how I could make something work, I started to think of how I'd like the API to look. How could I make the code reusable. I thought about the perspective of another dev using the code rather than the goal itself, since that eventually became the easy part.

Once you start thinking in terms of the API, and how you can design it so someone with minimal documentation could still use it (though you still document it!) you start wanting to hide the implementation etc, and all the other OOP ideas fall into place.

of course, I don't think it's something that can be taught. It's an evolution. When you first start programming, everything is unknown, so you don't have the brain power to focus on design. When you learn more, and you free up brain power you can start concentrating on these other things.

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