Any way to find out what the 35 year mistake was without being "engaged" for hours on that video?
When OOP went mainstream it pretty much was entirely about "compile time hierarchy of encapsulation that matches the domain model" and nothing else. His opinion is the standard way of doing OOP is a bad match for lots of software problems but became the one-size-fits-all solution as a result of ignorance.
Also he claims that history is being rewritten to some extent to say this wasn't the case and there was never a heavy emphasis on doing things that way.
This is a mistake is because it puts the broad-scale modularization boundaries of a system in the wrong places and makes the system brittle and inflexible. A better approach is one where large scale system boundaries fall along computational capability lines, as exemplified by modern Entity Component Systems. Class hierarchies that rigidly encode domain categorizations don't make for flexible systems.
Some of the earliest writers on object encapsulation, e.g. Tony Hoare, Doug Ross, understood this, but later language creators and promoters missed some of the subtleties of their writings and left us with a poor version of object-oriented programming as the accepted default.
> And another thing is if you look at the other branch,
> the branch that I'm not really covering very much
> in this talk, because again,
> we don't program in small talk these days, right?
> The closest thing you would get
> is maybe something like Objective-C.
> If there's some people out there using Objective-C,
> you know, like Apple was using that for a little while,
> so Objective-C kind of came
> from a small talk background as well.
Objective-C is basically Smalltalk retrofitted onto C, even more than C++ was Simula retrofitted onto C (before C++ gained template metaprogramming and more modern paradigms), so it makes sense that Muratori doesn't go much into it, given that he doesn't discuss Smalltalk much.
If we discount NeXT's time using it, Apple's only been using Objective-C for 28 years, just a little while. It also (barely) preceded C++.
- Encapsulation / interfaces is a good idea, a continuation of the earlier ideas of structured programming.
- Mutable state strewn uncontrollably everywhere is bad idea, even in a single-threaded case.
- Inheritance-based polymorphism is painful, both in the multiple (C++) and single (Java) inheritance cases. Composable interfaces / traits / typeclasses without overriding methods are logically and much more useful.
I watched over and over again people writing code to interfaces, particularly due to Spring, and then none of those interface ever got a second implementation done and were never, ever going to! It was a total waste of time, even for testing it was almost a total waste of time, but I guess writing stubbed test classes that could pretend to return data from a queue or a database was somewhat useful. The thing is, there were easier ways to achieve that.
The talk traces that mistake to Simula, where it was appropriately used, because it was intended to simulate the real world hierarchies. Then to C++ where it started to become used inappropriately, then to Java, where it became a universal Praxis to model all real world relationship as compile time hierarchies.
Object oriented programming.