fli:dereference

(fli:dereference pointer &key index type copy-foreign-object)

Answers the object pointer points at -- element index (default 0) of an array of them -- read as the pointer's type, or as type when given. Numbers, t / nil for a boolean type, an objc:objc-object-pointer for an object and a foreign pointer for a pointer; setf writes one. A structure or an array is not a Lisp value here: copy-foreign-object nil answers a foreign pointer to it, t a copy in freshly allocated memory, and the default :error signals. A null pointer or a pointer to :void without type signals. Part of the macOS-only fli package, beside objc -- the interpreter (java -jar, or the rontolisp native binary), a compiled .class / .jar and a --native executable for macOS on Apple silicon, never a .wasm. See the macOS GUI guide.

CL-USER> (fli:with-dynamic-foreign-objects ((n :int :initial-element 41))
           (setf (fli:dereference n) (+ 1 (fli:dereference n)))
           (fli:dereference n))
42