Object-oriented design is about message-passing; messages are more important than objects. Classes are completely irrelevant -- there's an entire branch of object-oriented language design without classes!
there’s an entire branch of object-oriented language design without classes!
That's not OOP anymore. There's definitely a lot of OOP code out there (especially in the Java world) that goes way too far with inheritance and class structures, and good OOP code relies a lot less on classes - but they are still used and a critical component of the style of programming.
Object-oriented design is about message-passing;
I'd argue that's an implementation detail rather than part of OOP. Also it's rarely used in modern OOP languages because it's just too slow*. Unfortunately when you take it away some patterns are lost, but the trade off is generally worth it.
(* when I used to work in Objective-C, message sending was often slower than all of the rest of my code combined and in tight loops I'd often rewrite my OOP code as procedural C code in order to have acceptable performance. Never need to do that in Swift, which doesn't do messages)
Whatever it may have become in later years, Alan Kay, who is often called "The Father of Object-oriented Programming", outlined the message-passing idea as the main concept he was driving at, originally.
Object-oriented design is about message-passing; messages are more important than objects. Classes are completely irrelevant -- there's an entire branch of object-oriented language design without classes!
That's not OOP anymore. There's definitely a lot of OOP code out there (especially in the Java world) that goes way too far with inheritance and class structures, and good OOP code relies a lot less on classes - but they are still used and a critical component of the style of programming.
I'd argue that's an implementation detail rather than part of OOP. Also it's rarely used in modern OOP languages because it's just too slow*. Unfortunately when you take it away some patterns are lost, but the trade off is generally worth it.
(* when I used to work in Objective-C, message sending was often slower than all of the rest of my code combined and in tight loops I'd often rewrite my OOP code as procedural C code in order to have acceptable performance. Never need to do that in Swift, which doesn't do messages)
Whatever it may have become in later years, Alan Kay, who is often called "The Father of Object-oriented Programming", outlined the message-passing idea as the main concept he was driving at, originally.
He also says that he probably misnamed it.
Here's a discussion in which the man himself makes a (small) appearance: https://softwareengineering.stackexchange.com/questions/46592/so-what-did-alan-kay-really-mean-by-the-term-object-oriented
JavaScript is an example of how OOP can be done without classes (before they were added to appease Java enthusiasts).