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>"Also, everything just feels "backwards" to me if that makes any sense." Because it is. Obj-C comes from the Smalltalk lineage by way of Alan Kay, using mess

>"Also, everything just feels "backwards" to me if that makes any sense." Because it is. Obj-C comes from the Smalltalk lineage by way of Alan Kay, using message passing [0] versus method invocation. It's a subtle difference with huge implications to how you design systems. Method invocation won out mostly because of Java and C++, but there was a time it wasn't clear which was the better OO paradigm. [0] https://en.m.wikipedia.org/wiki/Message_passing https://en.m.wikipedia.org/wiki/Message_passing

bunderbunder 2y ago
Message passing belongs up there with lisp, forth and pure functional programming as paradigms that are worth learning for "the profound enlightenment experience you will have when you finally get it." But I often see that my peers in the profession lack the kind of growth mentality that enables a person to see past the alienness of less algol-y languages. Quote from "How To Become a Hacker" by Eric S. Raymond: http://www.catb.org/esr/faqs/hacker-howto.html http://www.catb.org/esr/faqs/hacker-howto.html
- em-bee 2y ago
  see my comment above: https://news.ycombinator.com/item?id=42132104 https://news.ycombinator.com/item?id=42132104 i can't tell the difference and therefore i don't see what profound enlightenment experience i am supposed to have.
  - mpweiher 2y ago
    If you can't tell the difference, you didn't actually learn it. Doesn't mean you have to like it, but they are different.
    - em-bee 2y ago
      you may want to read the whole discussion following the linked comment to understand what i learned. if you have any additional insights i'd appreciate your input.
      - mpweiher 2y ago
        What makes you think I didn't?
        em-bee 2y ago
        well, if you did, then can you please tell me what i am missing? i have written a decent amount if smalltalk code, and even held workshops teaching smalltalk to others. and i have written lots of code in many other languages. i did see differences. the most awesome was when i wrote some code to respond to an http request, the code failed, the http request stalled, i fixed the code live, and then the http request resumed. but i can do the same in pike if i tried, and i expect in lisp and other languages too. and if that is the case then it supports my understanding that most OO languages use message passing. where then is the great revelation that comes from smalltalk?
        mpweiher 2y ago
        >> i can't tell the difference > i did see differences. Spot the difference. ;-) > but i can do the same in pike if i tried, and i expect in lisp and other languages too. Absolutely you can! You can even do it in C: write yourself a message-passing library in C. You might want to call it Objective-C. Or do a VM for Smalltalk. > where then is the great revelation that comes from smalltalk? The claim was not that the great revelation came from Smalltalk, but that it came from message passing: >>> Message passing belongs up there with lisp, forth and pure functional programming as paradigms that are worth learning for "the profound enlightenment experience you will have when you finally get it." Smalltalk isn't even mentioned in that little section about the enlightenment. And in fact, Smalltalk's form of message-passing is pretty limited, it only just extends beyond method invocation and it certainly can be (and is) frequently used just like method invocation. If you want to do more sophisticated things, you mostly have to go via the DNU handler, which is a bit hacky. And in fact, Alan Kay's famous OOPSLA '97 quip "I made up the term object oriented. And I can tell you I did not have C++ in mind." was followed immediately with the slightly less famous "So, the important thing here is: I have many of the same feelings about Smalltalk". https://www.youtube.com/watch?t=634&v=oKg1hTOQXoY&feature=youtu.be https://www.youtube.com/watch?t=634&v=oKg1hTOQXoY&feature=yo... And even message-passing is much broader: for example, with Higher Order Messaging, you can control how messages are delivered: to collections, on different threads, delayed, distributed (combine distributed + delayed and you get TeaTime/Croquet), conditionally only if the receiver understands the message, etc. https://en.wikipedia.org/wiki/Higher_order_message https://en.wikipedia.org/wiki/Higher_order_message https://www.youtube.com/watch?v=GBtqQwcJoN0 https://www.youtube.com/watch?v=GBtqQwcJoN0 And even that just scratches the surface. When you look at something like the Enterprise Integration Patterns, that's distributed asynchronous messaging, which opens up a whole other universe. Also: Erlang. https://www.enterpriseintegrationpatterns.com https://www.enterpriseintegrationpatterns.com https://stackoverflow.com/questions/3431509/is-erlang-object-oriented https://stackoverflow.com/questions/3431509/is-erlang-object...
  - igouy 2y ago
    fwiw 'what matters about an object is its protocol: the set of messages that it understands, and the way that it behaves in response to those messages. Nowadays, this is sometimes also referred to as the objectʼs interface. The key idea is that when we use an object, we focus on how it appears from the outside, and “abstract away from” its internal structure: more simply, that the internal structure of an object is hidden from all other objects. Thatʼs why I said “the set of messages that it understands,” and not “the set of methods that it implements.” In many languages they are the same, but I wanted to emphasise the external rather than the internal view.' "Object-oriented programming: Some history, and challenges for the next fifty years" Andrew P. Black https://doi.org/10.1016/j.ic.2013.08.002 https://doi.org/10.1016/j.ic.2013.08.002 So, a matter of emphasis?
pjmlp 2y ago
Java is heavily based in Smalltalk and Objective-C, even if it has a C++ like syntax for mainstream adoption. https://cs.gmu.edu/~sean/stuff/java-objc.html https://cs.gmu.edu/~sean/stuff/java-objc.html Even Java EE was actually a rebooted Objective-C based project done internally at Sun during the OpenSTEP days, aka Distributed Objects Everywhere.
em-bee 2y ago
i have learned smalltalk, common lisp, java, python, ruby, perl, php, C, javacript and a few other languages, and i still do not understand the difference between message passing and function invocation. they look the same to me. according to wikipedia the difference is "In contrast to the traditional technique of calling a program by name, message passing uses an object model to distinguish the general function from the specific implementations. The invoking program sends a message and relies on the object to select and execute the appropriate code." Method invocation won out mostly because of Java and C++ but according to the wikipedia article java uses message passing. supposedly the distinction is that i can have a generic method that gets called if a named method can not be found. in smalltalk that's doesNotUnderstand: in ruby it's method_missing. javascript used to have __noSuchMethod__, in php i can overload __call, in pike i do the same with defining a method called `(), and many more. so are they all using message passing? and then if java is supposed to use message passing and javascript removed __noSuchMethod__ it seems that alone can't be the distinction. if there is a distinction at all then it look more like an implementation detail that does not actually affect what kind of code you can write, and more importantly, based on that it is not at all clear that method invocation won out.
- astrange 2y ago
  The difference is NSInvocation. A function pointer doesn't capture the arguments to the function, but a message does. Also, you can change the destination of a message send at runtime, but you can't change the destination of a function call unless you're dtrace and can do code patching.
  - em-bee 2y ago
    ok, so that means message passing needs a runtime, and it can be assumed that pretty much every language that has a runtime uses message passing. more evidence that it is message passing that won out. and the profound enlightenment ( https://news.ycombinator.com/item?id=42130432 https://news.ycombinator.com/item?id=42130432 ) is not specific to message passing but about a dynamic language runtime. being able to intercept messages/function calls is just one of the benefits of that.

bunderbunder 2y ago

Message passing belongs up there with lisp, forth and pure functional programming as paradigms that are worth learning for "the profound enlightenment experience you will have when you finally get it." But I often see that my peers in the profession lack the kind of growth mentality that enables a person to see past the alienness of less algol-y languages. Quote from "How To Become a Hacker" by Eric S. Raymond: http://www.catb.org/esr/faqs/hacker-howto.html http://www.catb.org/esr/faqs/hacker-howto.html

em-bee 2y ago
see my comment above: https://news.ycombinator.com/item?id=42132104 https://news.ycombinator.com/item?id=42132104 i can't tell the difference and therefore i don't see what profound enlightenment experience i am supposed to have.
- mpweiher 2y ago
  If you can't tell the difference, you didn't actually learn it. Doesn't mean you have to like it, but they are different.
  - em-bee 2y ago
    you may want to read the whole discussion following the linked comment to understand what i learned. if you have any additional insights i'd appreciate your input.
    - mpweiher 2y ago
      What makes you think I didn't?
      - em-bee 2y ago
        well, if you did, then can you please tell me what i am missing? i have written a decent amount if smalltalk code, and even held workshops teaching smalltalk to others. and i have written lots of code in many other languages. i did see differences. the most awesome was when i wrote some code to respond to an http request, the code failed, the http request stalled, i fixed the code live, and then the http request resumed. but i can do the same in pike if i tried, and i expect in lisp and other languages too. and if that is the case then it supports my understanding that most OO languages use message passing. where then is the great revelation that comes from smalltalk?
        mpweiher 2y ago
        >> i can't tell the difference > i did see differences. Spot the difference. ;-) > but i can do the same in pike if i tried, and i expect in lisp and other languages too. Absolutely you can! You can even do it in C: write yourself a message-passing library in C. You might want to call it Objective-C. Or do a VM for Smalltalk. > where then is the great revelation that comes from smalltalk? The claim was not that the great revelation came from Smalltalk, but that it came from message passing: >>> Message passing belongs up there with lisp, forth and pure functional programming as paradigms that are worth learning for "the profound enlightenment experience you will have when you finally get it." Smalltalk isn't even mentioned in that little section about the enlightenment. And in fact, Smalltalk's form of message-passing is pretty limited, it only just extends beyond method invocation and it certainly can be (and is) frequently used just like method invocation. If you want to do more sophisticated things, you mostly have to go via the DNU handler, which is a bit hacky. And in fact, Alan Kay's famous OOPSLA '97 quip "I made up the term object oriented. And I can tell you I did not have C++ in mind." was followed immediately with the slightly less famous "So, the important thing here is: I have many of the same feelings about Smalltalk". https://www.youtube.com/watch?t=634&v=oKg1hTOQXoY&feature=youtu.be https://www.youtube.com/watch?t=634&v=oKg1hTOQXoY&feature=yo... And even message-passing is much broader: for example, with Higher Order Messaging, you can control how messages are delivered: to collections, on different threads, delayed, distributed (combine distributed + delayed and you get TeaTime/Croquet), conditionally only if the receiver understands the message, etc. https://en.wikipedia.org/wiki/Higher_order_message https://en.wikipedia.org/wiki/Higher_order_message https://www.youtube.com/watch?v=GBtqQwcJoN0 https://www.youtube.com/watch?v=GBtqQwcJoN0 And even that just scratches the surface. When you look at something like the Enterprise Integration Patterns, that's distributed asynchronous messaging, which opens up a whole other universe. Also: Erlang. https://www.enterpriseintegrationpatterns.com https://www.enterpriseintegrationpatterns.com https://stackoverflow.com/questions/3431509/is-erlang-object-oriented https://stackoverflow.com/questions/3431509/is-erlang-object...
- igouy 2y ago
  fwiw 'what matters about an object is its protocol: the set of messages that it understands, and the way that it behaves in response to those messages. Nowadays, this is sometimes also referred to as the objectʼs interface. The key idea is that when we use an object, we focus on how it appears from the outside, and “abstract away from” its internal structure: more simply, that the internal structure of an object is hidden from all other objects. Thatʼs why I said “the set of messages that it understands,” and not “the set of methods that it implements.” In many languages they are the same, but I wanted to emphasise the external rather than the internal view.' "Object-oriented programming: Some history, and challenges for the next fifty years" Andrew P. Black https://doi.org/10.1016/j.ic.2013.08.002 https://doi.org/10.1016/j.ic.2013.08.002 So, a matter of emphasis?

pjmlp 2y ago

Java is heavily based in Smalltalk and Objective-C, even if it has a C++ like syntax for mainstream adoption. https://cs.gmu.edu/~sean/stuff/java-objc.html https://cs.gmu.edu/~sean/stuff/java-objc.html Even Java EE was actually a rebooted Objective-C based project done internally at Sun during the OpenSTEP days, aka Distributed Objects Everywhere.

em-bee 2y ago

i have learned smalltalk, common lisp, java, python, ruby, perl, php, C, javacript and a few other languages, and i still do not understand the difference between message passing and function invocation. they look the same to me. according to wikipedia the difference is "In contrast to the traditional technique of calling a program by name, message passing uses an object model to distinguish the general function from the specific implementations. The invoking program sends a message and relies on the object to select and execute the appropriate code." Method invocation won out mostly because of Java and C++ but according to the wikipedia article java uses message passing. supposedly the distinction is that i can have a generic method that gets called if a named method can not be found. in smalltalk that's doesNotUnderstand: in ruby it's method_missing. javascript used to have __noSuchMethod__, in php i can overload __call, in pike i do the same with defining a method called `(), and many more. so are they all using message passing? and then if java is supposed to use message passing and javascript removed __noSuchMethod__ it seems that alone can't be the distinction. if there is a distinction at all then it look more like an implementation detail that does not actually affect what kind of code you can write, and more importantly, based on that it is not at all clear that method invocation won out.

astrange 2y ago
The difference is NSInvocation. A function pointer doesn't capture the arguments to the function, but a message does. Also, you can change the destination of a message send at runtime, but you can't change the destination of a function call unless you're dtrace and can do code patching.
- em-bee 2y ago
  ok, so that means message passing needs a runtime, and it can be assumed that pretty much every language that has a runtime uses message passing. more evidence that it is message passing that won out. and the profound enlightenment ( https://news.ycombinator.com/item?id=42130432 https://news.ycombinator.com/item?id=42130432 ) is not specific to message passing but about a dynamic language runtime. being able to intercept messages/function calls is just one of the benefits of that.