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Alan Kay on the misunderstanding of OOP (1998)

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Re: Alan Kay on the misunderstanding of OOP (1998)

#21

Post by ridiculous_fish »

elchief wrote: post #8

How is messaging different than calling a method?

One example is the HTTP GET request. This was originally conceived of as a file download, where the URL path is mapped directly to filesystem paths. GET as an RPC: "download the file at this location."

But in modern thinking, HTTP GET is a request with abstract semantics. The URL's path is abstract, and may be interpreted arbitrarily by the server. The client has no idea whether the request is serviced by a simple sendfile() or a fully dynamic program. HTTP GET is no longer an RPC, it is now a message.

A key difference is whether your function call is a request for concrete or abstract behavior. If you answer "abstract," then the call itself must be reifiable data, which can be sliced and diced in ways hidden from the caller.

Re: Alan Kay on the misunderstanding of OOP (1998)

#22

Post by lacker »

stevedonovan wrote: post #18
lacker wrote: post #14

IMO the problem with object-oriented programming is that it turned into the standard curriculum for peoples' first semester of computer science, rather than being yet another interesting concept that advanced programmers would ponder. And the way we handle "the standard CS curriculum" sucks. (In the USA at least.) For example, AP Computer Science requires Java and tries to teach stuff like designing inheritance hiera…

OOP made sense to people who already knew structured programming and understood functional decomposition (what we now call 'refactoring'). Perhaps education should start with that and then justify OOP? I remember reading about the original LOGO experiments; one thing kids do not spontaneously do is break up their monolithic actions into sensible functions.

Yeah "breaking up a complex function into simpler functions" is a great example of something that isn't taught well today, yet is simpler and more critical than what we try to teach people in intro courses.

I think of it in analogy to math. OOP is like topology - it's definitely useful in some cases, it's not too hard for an experienced mathematician to get the basics, and yet in a lot of situations it's irrelevant and it doesn't really belong in the first class you take.

Being able to solve fizzbuzz is like doing arithmetic. If you can't solve fizzbuzz then you aren't going to be able to really get any advanced concepts. It's like you can't be a good mathematician if you can't figure out whether 351 is an odd number - you need to learn the basics first, even if "real math isn't about arithmetic".

Sadly, you can tell if you do a lot of phone screens that many people who graduate with CS degrees still can't code fizzbuzz. Our CS education is busted right at the beginning. It needs to get the basics right, like, can you write loops, can you write functions. Today it is failing at that.

Re: Alan Kay on the misunderstanding of OOP (1998)

#23

Post by elchief »

ridiculous_fish wrote: post #21
elchief wrote: post #8

How is messaging different than calling a method?

One example is the HTTP GET request. This was originally conceived of as a file download, where the URL path is mapped directly to filesystem paths. GET as an RPC: "download the file at this location." But in modern thinking, HTTP GET is a request with abstract semantics. The URL's path is abstract, and may be interpreted arbitrarily by the server. The client has no idea whether the request is serviced by a simple se…

I'll buy that

Re: Alan Kay on the misunderstanding of OOP (1998)

#24

Post by robohamburger »

mej10 wrote: post #7
blihp wrote: post #4

Earlier quoted context omitted.

Squeak[1]/Smalltalk? (i.e. have you worked with what he would consider a 'real' message-oriented OO language?) [1] http://squeak.org/downloads/

I played around with Squeak many years ago, but might appreciate it more now. What recently spurred more confusion on this topic was Alan Kay's discussion with Rich Hickey during the AMA the other day. https://news.ycombinator.com/item?id=11945722 I found it really hard to understand what Alan Kay is actually talking about. Saying things like > This is why "the objects of the future" have to be ambassadors that can n…

Probably totally wrong but here is what I took away:

It kind of reminds me of bounded contexts like the ones from http://martinfowler.com/bliki/BoundedContext.html

When being complex information systems you ended with subtle drifting in what something actually means from person to person or over time.

More directly in regards to having ambassadors working with unseen objects:

Seems like you would need some shared "language" the objects speak otherwise communication is impossible. Maybe a better way of describing intent or information? Like some kind of logical or declarative model + messages.

Also come to think of it reminds me of: https://en.wikipedia.org/wiki/Intentional_programming

Re: Alan Kay on the misunderstanding of OOP (1998)

#25

Post by DigitalJack »

ridiculous_fish wrote: post #21
elchief wrote: post #8

How is messaging different than calling a method?

One example is the HTTP GET request. This was originally conceived of as a file download, where the URL path is mapped directly to filesystem paths. GET as an RPC: "download the file at this location." But in modern thinking, HTTP GET is a request with abstract semantics. The URL's path is abstract, and may be interpreted arbitrarily by the server. The client has no idea whether the request is serviced by a simple se…

Can you define "reifiable" for me? I come across it a fair bit in clojure, but I still don't really understand what the term means.

Re: Alan Kay on the misunderstanding of OOP (1998)

#26

Post by robohamburger »

panic wrote: post #16
mej10 wrote: post #7

Earlier quoted context omitted.

I played around with Squeak many years ago, but might appreciate it more now. What recently spurred more confusion on this topic was Alan Kay's discussion with Rich Hickey during the AMA the other day. https://news.ycombinator.com/item?id=11945722 I found it really hard to understand what Alan Kay is actually talking about. Saying things like > This is why "the objects of the future" have to be ambassadors that can n…

Here's my understanding of the general idea (let me know if I got something wrong!). Say you have a bunch of computers with different software and hardware. You come up with a cool new image format called "PJEG". To get the images to show up on all the computers, you typically do the following: * Publish a PJEG spec * Define a .pjeg extension and let everyone know that means it's a PJEG file * Write a PJEG encoder/vi…

An interesting idea but wouldn't this require a universal interpreter and format to decode to?

Seems a like certain things on the web already. Just the bounds on what the "file" is are a bit messy.

Re: Alan Kay on the misunderstanding of OOP (1998)

#27

Post by _pmf_ »

elchief wrote: post #8

How is messaging different than calling a method?

For dynamically typed languages, this distinction is less pronounced, but in general, the caller assumes less about the callee (i.e. you can send any message to any object).

It also allows transparent routing/delegating and, in some cases (void result type), transparent multiplexing.

Re: Alan Kay on the misunderstanding of OOP (1998)

#28

Post by Matthias247 »

elchief wrote: post #8

How is messaging different than calling a method?

I think it could be different if the intention is that the message (or method body) is always executed in the context of the called object. E.g. in an own thread, which is used instead of the thread/callstack of the the caller, and which is also exclusivly used even if the method is called from multiple threads - which would elide the need for synchronization.

However as far as I understand most implementations that talk about messaging (e.g. ObjectiveC) do exactly the same thing as plain method calls. The difference seems to be that there is more dynamic in the "messaging" (can send any message to an object or can write a "method" that processes arbitrary messages) - but for me that sounds more like the difference between static and dynamic languages than as a completely different messaging concept instead of methods. I don't know Squeal and Smalltalk so maybe I'm missing something here

Re: Alan Kay on the misunderstanding of OOP (1998)

#29

Post by jcoffland »

panic wrote: post #16
mej10 wrote: post #7

Earlier quoted context omitted.

I played around with Squeak many years ago, but might appreciate it more now. What recently spurred more confusion on this topic was Alan Kay's discussion with Rich Hickey during the AMA the other day. https://news.ycombinator.com/item?id=11945722 I found it really hard to understand what Alan Kay is actually talking about. Saying things like > This is why "the objects of the future" have to be ambassadors that can n…

Here's my understanding of the general idea (let me know if I got something wrong!). Say you have a bunch of computers with different software and hardware. You come up with a cool new image format called "PJEG". To get the images to show up on all the computers, you typically do the following: * Publish a PJEG spec * Define a .pjeg extension and let everyone know that means it's a PJEG file * Write a PJEG encoder/vi…

This would require that any new image format only did things that were foreseen by the creators of the metalanguage. If the metalanguage is Turing complete then it's just an interpreter. Python, for example, could be your metalanguage. Then I would argue that we already have this.
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