Hacker News Reader

Comment by Jtsummers | Hacker News Reader

What would it mean to have a MOP for a language which doesn't have objects in the OO sense? Especially C.

Well, in C you have function calls, so you can still do reification on that, turn it in to a value (ie a record that holds the parameters and the pointer of the function) and fiddle with it. Some examples:

  - you can send it to another machine turning it into RPC, and you can encrypt (some of) the parameters because of this
  - you can add save the program state before you execute it for checkpointing purposes
  - you can log the parameters for tracing
  - ...

Presumably it would standardise the current way of doing OO in C while the MOap is being standardised.

Just because some language does not have classes doesn't mean you cannot implement a functional substitute.

isn't CLOS OO based on generic functions and not objects? as far as I know Lisp doesn't have objects in the OO sense either.

Objects are instances of classes in CLOS. Classes, Methods, Generic Functions, ... are also instances of classes. Classes support multiple inheritance. Instances have an identity, slots and a class.

CLOS does not use methods attached to classes, which can be invoked by message sending or similar. Instead CLOS uses Generic Functions which consist of one or more Methods. Methods are dispatched over classes, using possibly multiple arguments. Generic Functions are themselves objects and they are defined outside of classes. When a Generic Function gets called, all the applicable Methods are combined to an Effective Method that then will be executed.

Reply on news.ycombinator.com