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llmslave2last Wednesday at 7:38 AM1 replyview on HN

Anything where you have literal "instances" of something with common state/behaviour is prime for inheritance, but that's different from trying to model a domain as a set of hierarchal objects.

But I do like classes - you can use them without inheritance, and the other stuff that comes with them (encapsulation, polymorphism, etc) fits my mental model. [0] Classes are just syntactic sugar over closures at the end of the day.

But inheritance is best when it's limited and shallow.

0:

  The venerable master Qc Na was walking with his student, Anton. Hoping
  to prompt the master into a discussion, Anton said "Master, I have
  heard that objects are a very good thing - is this true?" Qc Na looked
  pityingly at his student and replied, "Foolish pupil - objects are
  merely a poor man's closures."

  Chastised, Anton took his leave from his master and returned to his
  cell, intent on studying closures. He carefully read the entire
  "Lambda: The Ultimate..." series of papers and its cousins, and
  implemented a small Scheme interpreter with a closure-based object
  system. He learned much, and looked forward to informing his master of
  his progress.

  On his next walk with Qc Na, Anton attempted to impress his master by
  saying "Master, I have diligently studied the matter, and now
  understand that objects are truly a poor man's closures." Qc Na
  responded by hitting Anton with his stick, saying "When will you
  learn? Closures are a poor man's object." At that moment, Anton became
  enlightened.

Replies

ahartmetzlast Wednesday at 10:01 AM

I guess closures in languages like Scheme can have multiple "methods"? In C++ and Rust, closures (lambdas) are one function with attached state variables. I guess there are ways to attach more callables to a bag of state, but they would involve one lambda for each callable and shared state captured by reference (and good luck dealing with lifecycle issues).

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