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I think your analogy is going in a better direction. I had the same idea after taking a look at Squeak for a while. What would need to be added to your analogy

I think your analogy is going in a better direction. I had the same idea after taking a look at Squeak for a while. What would need to be added to your analogy is a notion of design. You see, in Smalltalk, for example, your programming takes place in the messages. So, even the daemons (which, for the sake of argument, we could think of as analogies to objects), which would be the senders and receivers of messages would be made out of the same stuff, not C/C++. So, this is a pretty dramatic departure from the way Unix operates. What this should suggest is that the semantic connection between objects is late-bound. Think of them as servers. Secondly, in the typical Smalltalk implementation, there is still compilation, but it's incremental. You compile expressions and methods, not the whole body of source code for the whole system. What's really different about it is since the semantic actions are late-bound, you can even compile something while a thread is executing through the code you're compiling. So, you get nearly instant feedback on changes for free. Bret Victor's notion of programming environments blurs the axes you're talking about even more, so that you don't have to do two steps to see your change, while a thread is running (edit, then compile). You can see the effect of the change the moment you change an element, such as the upper bound of an iterative loop. To make it even more dynamic, he tied GUI elements (sliders) to such things as the loop parameters, so that you don't have to laboriously type the values to try them out. You can just change the slider, and see the effects of the change in a loop's range very quickly, such that it almost feels like you're using a tool-based design space, rather than programming. I don't know how this was done in ST-78, but in ST-80, at least in accounts I've heard from people who've used versions of it, and in the version of Squeak I've used from time to time, the source code is not technically stored with the class object, though the system keeps references to the appropriate pieces of source code, and their revisions, mapping them to the classes in the system, so that when you tell the system you want to look at the source code for a class, it pulls up the appropriate version of the code in an editor. Source code is stored in a separate file, and Smalltalk has a version control system that allows reviewing of source code edits, and reversion of changes (undo). The class object typically exists in the Smalltalk image as compiled code. There are many things that are different about this vs. what you typically practice in CS, but addressing your point about data, in OOP, objects are supposed to take the place of data. In OOP, data contains its own semantics. It inverts the typical notion of procedures acting on data. Instead, data contains procedures. It's an active "live" part of the programming that you do. So, yes, data is persisted, along with its procedures. A simple example in Smalltalk is: 2 + 2. If we analyze what's going on, the "2"'s are the pieces of data, the objects/servers, and "+" is used to reference a method in one of the data instances, but it doesn't stop there. The "2" objects communicate with each other to do the addition, getting the result: 4. As you can tell implicitly, "2 + 2" is also source code, to generate the semantic actions that generate the result.

alankay1 9y ago
"More or less" ... I can see that it's hard after decades of "data-centric" perspectives to think in terms of "computers" rather than "data", and about semantics rather than pragmatics. It's not "data contains procedures" but that objects are (a) semantically computers, and are impervious to attack from the outside (a computer has to let an attack happen via its own internal programming), and (b) what's inside can be anything that is able to deal with messages in a reasonable way. In Smalltalk, these are more objects (there are only objects in Smalltalk). The way the internals of typical Smalltalk objects are organized could be done better (we used several schemes, but all of them had variables and methods (which were also objects). So "2" is not "data" in Smalltalk (unfortunately, it is in Java, etc.) We had planned that the interior of objects should be an "address space of objects" because this is a better and more recursive way to do modularization, and to allow a different inter-viewing scheme (we eventually did some of this for the Etoys system for children about 20 years ago). But the physical computers at Parc were tiny, and the code we could run was tiny (the whole system in the Ted Nelson demo video was a little over 10,000 lines of code for everything). So we stayed with our top priority: to make a real and highly interactive system that was very comprehensive about what it and the user could do together.
- mmiller 9y ago
  I was using "data" in the spirit of a saying I heard many years ago in CS, that, "Data is code, and code is data." It seems that people in CS are still familiar with this phrase. I was focusing on the latter part of that phrase. I was trying to answer the question that I think is often implied once you start talking to people about real OOP, "What about data?" I almost don't like the term "data" when talking about this, because as you say, it gets one away from the focus on semantics, but whenever you're talking to people in the computing field, such as it is, I think this question is unavoidable, because people are used to thinking of code and information as separate, hence the notion of data structures. People need a way to translate in their minds between what they've done with information before, and what it can be. So, I used the term "data" to talk about "literal objects" (like "2", or other kinds of input), but I was using the description of "processors" (ie. computers), "containing procedures," which can also be thought of as "operators." I think the idea of an "inversion" is quite apt, because as you've said before, the idea of data structures is that you have procedures acting on data. With real objects, you still have the same essential elements in programming, the same stuff to deal with, but the kinds of things programmers typically think about as "data" are objects/computers in OOP, with intrinsic semantics. So, you're still dealing with things like "2", just as procedures acting on data do, but instead of it being just a "dead" symbol, that can't do anything, "2" has semantics associated with an interface. It's a computer.

alankay1 9y ago

"More or less" ... I can see that it's hard after decades of "data-centric" perspectives to think in terms of "computers" rather than "data", and about semantics rather than pragmatics. It's not "data contains procedures" but that objects are (a) semantically computers, and are impervious to attack from the outside (a computer has to let an attack happen via its own internal programming), and (b) what's inside can be anything that is able to deal with messages in a reasonable way. In Smalltalk, these are more objects (there are only objects in Smalltalk). The way the internals of typical Smalltalk objects are organized could be done better (we used several schemes, but all of them had variables and methods (which were also objects). So "2" is not "data" in Smalltalk (unfortunately, it is in Java, etc.) We had planned that the interior of objects should be an "address space of objects" because this is a better and more recursive way to do modularization, and to allow a different inter-viewing scheme (we eventually did some of this for the Etoys system for children about 20 years ago). But the physical computers at Parc were tiny, and the code we could run was tiny (the whole system in the Ted Nelson demo video was a little over 10,000 lines of code for everything). So we stayed with our top priority: to make a real and highly interactive system that was very comprehensive about what it and the user could do together.

mmiller 9y ago
I was using "data" in the spirit of a saying I heard many years ago in CS, that, "Data is code, and code is data." It seems that people in CS are still familiar with this phrase. I was focusing on the latter part of that phrase. I was trying to answer the question that I think is often implied once you start talking to people about real OOP, "What about data?" I almost don't like the term "data" when talking about this, because as you say, it gets one away from the focus on semantics, but whenever you're talking to people in the computing field, such as it is, I think this question is unavoidable, because people are used to thinking of code and information as separate, hence the notion of data structures. People need a way to translate in their minds between what they've done with information before, and what it can be. So, I used the term "data" to talk about "literal objects" (like "2", or other kinds of input), but I was using the description of "processors" (ie. computers), "containing procedures," which can also be thought of as "operators." I think the idea of an "inversion" is quite apt, because as you've said before, the idea of data structures is that you have procedures acting on data. With real objects, you still have the same essential elements in programming, the same stuff to deal with, but the kinds of things programmers typically think about as "data" are objects/computers in OOP, with intrinsic semantics. So, you're still dealing with things like "2", just as procedures acting on data do, but instead of it being just a "dead" symbol, that can't do anything, "2" has semantics associated with an interface. It's a computer.