With classic (Java, C#, and C++ to some extent) OOP, one can model shared behavior and data between classes by making those classes inherit from some common (absctract) base class with the appropriate methods and data. By making the methods suitably granular, the base class can then make small tweak…

UML diagrams are essentially a (relatively) standard way to lay out all of the relationships (is-a, via a normal arrow; has-a, via a diamond arrow; etc.) between classes in an OOP system. They can also encode and visualize things like public methods. I've found it to be helpful to plan out my heavil…

I know what UML diagrams are about. My difficulty with such diagrams is: I cannot fathom how program control flow goes on in the diagram. I cannot fathom how data flows through the system. I have no idea how one could chop that up for parallel execution. Basically, if I was hired to imp…

You avoided the question. I didn't mean to, sorry. It's part of a spec to code to. I made it for myself, however, and I have other information in my head with control flow, data flow, parallelization, etc. It wasn't originally meant to be complete — just enough to overcome the fact that my memor…

This is a hard one to answer because the design is so interconnected it’s hard to pick out a small piece to talk about. The general shape is certainly compatible with Rust, so the question is then how to implement the individual pieces ergonomically. Some thoughts on how I might go about this des…

In general, this issue doesn't really come up in Rust because the whole idiomatic programming style isn't really about shared state or other classic OOP design principles. As for a potential, quite easy solution if you really really need this, you can include a method in a trait that returns a refe…

"Composition over inheritance" does not mean "replace inheritance with composition". Composition alone is less powerful than inheritance, because inheritance is composition plus shared behavior plus some other stuff. If all you had in Rust was everything that's in Java, but no inheritance, Rust woul…

[image] trentj: If all you had in Rust was everything that's in Java, but no inheritance, Rust would be a less capable language. With my tendency towards picking nits I would be happier if that were "less expressive language" or some such. As far as I know all languages we might discuss here …

I think I have just had a revelation! I have possibly realized why C++, Java, C# and that style of OOP tsunami going on for decades has upset my mind. Let's think about that word "inheritance". As used in C++ and other languages. It is a total misnomer, the abstraction is wrong. Consider this: I…

To take the analogy a bit further, you're composed of different bits of code from your parents. For example, the functionality from two pieces of code called OCA2 and HERC2 determines the implementation of the melanocytes in your irises, and contributes to whether your eyes appear blue or brown.

Wikipedia is quite good on the benefits of composition over inheritance: [image] Composition over inheritance | Benefits To favor composition over inheritance is a design principle that gives the design higher flexibility. It is more natural to build business-domain classes out of various…

With composition over inheritance in Rust, how does one implement shared state to go with shared behaviour?

help

TomP August 16, 2020, 9:23pm 15

Perhaps Rust Koan #2 will provide some insight into why Rust prefers a more flexible alternative than inheritance.

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With composition over inheritance in Rust, how does one implement shared state to go with shared behaviour?

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