Methods Should Be Object Safe (nora.codes)

submitted 6 months ago by armchair_progamer@programming.dev to c/rust@programming.dev

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[-] kevincox@lemmy.ml 10 points 6 months ago

In my experience taking a term that is widely used and attempting to give it a more specific meaning doesn't end well. If people are using "method" interchangeably with "associated function" right now it will be an endless battle of trying to make people stop using the term "sloppily" when it isn't sloppy it was just the original meaning.

[-] armchair_progamer@programming.dev 7 points 6 months ago* (last edited 6 months ago)

I could understand method = associated function whose first parameter is named self, so it can be called like self.foo(…). This would mean functions like Vec::new aren’t methods. But the author’s requirement also excludes functions that take generic arguments like Extend::extend.

However, even the above definition gives old terminology new meaning. In traditionally OOP languages, all functions in a class are considered methods, those only callable from an instance are “instance methods”, while the others are “static methods”. So translating OOP terminology into Rust, all associated functions are still considered methods, and those with/without method call syntax are instance/static methods.

Unfortunately I think that some people misuse “method” to only refer to “instance method”, even in the OOP languages, so to be 100% unambiguous the terms have to be:

Associated function: function in an impl block.
Static method: associated function whose first argument isn’t self (even if it takes Self under a different name, like Box::leak).
Instance method: associated function whose first argument is self, so it can be called like self.foo(…).
Object-safe method: a method callable from a trait object.