For a course project I've been working on adding generators to contracts for use with contract-random-generate, and I've been trying to construct classes and objects from simple object/c contracts. When trying to find a way to functionally create a class at runtime, I came across the `make-primitive-class` function in class-internal.rkt.
This function is exported, and available at a plain racket repl, but has no documentation that I have been able to find and the comments about it in class-internal.rkt seem to be incorrect. Trying to call it from the repl has problems also, for example (ignoring for a moment that the arguments aren't of the expected types) -> (make-primitive-class #f #f 'foo object% null #f null null null null) ; compose-class: arity mismatch; ; the expected number of arguments does not match the given number ; expected: 28 ; given: 27 The definition is in terms of compose-class and is just missing a `null` argument for the abstract-names, but even after fixing that in my local branch there is a discrepancy with the comments regarding it's first argument `make-struct:prim`. ; The `make-struct:prim' function takes prop:object, a class, ; a preparer, a dispatcher function, an unwrap property, ; an unwrapper, and a property assoc list, and produces: ; * a struct constructor (must have prop:object) ; * a struct predicate ; * a struct type for derived classes (mustn't have prop:object) ; ; The supplied preparer takes a symbol and returns a num. ; ; The supplied dispatcher takes an object and a num and returns a method. ; ; The supplied unwrap property is used for adding the unwrapper ; as a property value on new objects. ; ; The supplied unwrapper takes an object and returns the unwrapped ; version (or the original object). ; ; When a primitive class has a superclass, the struct:prim maker ; is responsible for ensuring that the returned struct items match ; the supertype predicate. This suggests that make-struct:prim should take 7 arguments, but passing a function of 7 arguments to it from the repl produces: -> (make-primitive-class (lambda (a b c d e f g) (values #f #f #f)) #f 'foo object% null #f null null null null) ; #<procedure>: arity mismatch; ; the expected number of arguments does not match the given number ; expected: 7 ; given: 5 Also as far as I can tell `make-primitive-class` is never used in the code base, it is defined in class-internal.rkt, but can be commented out without seeming to break anything else. Does anyone know if there is a purpose for this function, or if there is documentation somewhere on the functions I need to pass it in order to construct a class. I think I'm starting to get a better idea of how it might work from reading more of class-internal.rkt and how the class* macro expands, but any guidance would be appreciated. Thanks Dan _________________________ Racket Developers list: http://lists.racket-lang.org/dev
