I am fascinated, though, by your claim that Lisp also used this term... before reading it I would have been 100% sure that it didn't. I just spent ten minutes trying to find documentation of this, and can't find it... but I am not a native speaker of Lisp and so don't always know where to look; can you point me at a reference? (FWIW, I know of the meta-object protocol, which afaik is a singular thing at a different level of abstraction, and I know about classes and methods and generic functions and mulmethods, which seem like what you are talking about but aren't described by protocol?)
Where do protocols originate from, I don't know. Maybe Smalltalk. But I first met them in Common Lisp ecosystem.
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https://github.com/franzinc/clim2/blob/master/utils/protocol...
https://github.com/franzinc/clim2/blob/master/clim/stream-de...
https://github.com/dkochmanski/clim-tos/graphs/contributors
Two lessons I learned:
One, Common Lisp code is surprisingly stable over time, with 90% of it still working on CCL/SBCL even though the codebase predates the language standard and is older than I am (don't be mislead by that 1991 on Github, it's much older).
Two, oh my god, trying to understand a large codebase seriously abusing :before/:after/:around methods in large class graphs is not an easy task, though arguably it's more of an issue with available tooling. With better ways to explore runtime program state, it would be much easier to understand and improve such code. I may have written about this last night here: https://mastodon.technology/@temporal/100646861775747986.
Also fun fact, this project is the only case where macroexpanding code crashed my SBCL...
Anyway, let that codebase be and serve as a historical reminder; for more modern implementation of CLIM standard, I'll direct everyone to https://common-lisp.net/project/mcclim/.
Quite likelym as another Guy (Steele) responsible for Java was also a big name in the Lisp world, including chairing the committee that wrote ANSI standard for Common Lisp. In the Lisp world, protocols were a known concept. In CL nomenclature, a protocol is a set of generic functions and types used by those functions. Which is kind of like a Java interfaces, except with multiple dispach based on any of the arguments instead of the typical single dispatch of Java and friends.
For example from TFA, a CL protocol would be a #'draw generic function and a 'drawable and 'renderer abstract types. The particular #'draw methods could be specialized on either argument (or both), and we could also imagine another protocol consisting of (the same) renderer type and some geometry-related generic functions.
Point being, protocols are both an old and very useful concept, and like usual, C++/Java-like languages only allow expressing a small subset of it.