I am following the book the ray tracer challenge .. I have created a vector3 and color defstruct
(defstruct (vector3
(:conc-name nil)
(:constructor v3 (x y z w)))
(x 0.0 :type float)
(y 0.0 :type float)
(z 0.0 :type float)
(w 0.0 :type float))
(defstruct (colors
(:conc-name nil)
(:constructor colors (r g b w)))
(r 0.0 :type float)
(g 0.0 :type float)
(b 0.0 :type float)
(w 0.0 :type float))
and some other functions like a scale multiplier
(defun vector-scalar (s v1)
(vector3 (* s (x v1))
(* s (y v1))
(* s (z v1))
(* s (w v1))))
but when I try and load the file I am getting errors such as
caught WARNING:
; Derived type of COMMON-LISP-USER::V1 is
; (VALUES COMMON-LISP-USER::VECTOR3 &OPTIONAL),
; conflicting with its asserted type
; COMMON-LISP-USER::COLORS.
; See also:
; The SBCL Manual, Node "Handling of Types"
I thought that whatever was inside a procedure had local scope so I do not understand why what I would consider an input for a function is being confused with a defstruct. If I load just the vector defstruct I do not get the error.
My worry is that any defstruct that I create that has four parameters will become confused with the vector3
I'm not sure how to resolve this problem because I don't actually understand whats wrong to start with.
Both of your structure definitions define an accessor named w which therefore can't exist. SBCL is not properly noticing this but instead making inferences about the type of the variable which can never be true (it's assuming based on what I suppose is the last definition of w it saw that it's a colors but then based on one of the other accessors that it must be a vector3).
If you want multiple distinct classes to have the same accessors, you need to use defclass not defstruct: defclass defines accessors as generic functions.