[Cffi-devel] Lists of METAOBJECTS and FOREIGN-ALLOC

[Joeish W]

I have this conditional from a cond statement I need to satisfy


    ((listp (first args))
     (c-arr-to-vector-point (first args)))


The (first args)  will be this but it should be able to have  an infinite number 
of (point i j) in it.

(foreign-alloc :pointer :initial-contents  (LIST (POINT 1 2) (POINT 3 4)))


The thing is that the output of (point i j) is a metaobject e.g. #<CV-POINT {10038888E3}> . That is how I have my return for point defined. When I need to use foreign-alloc to define an array of point I have to  do it like this...


(foreign-alloc :pointer :initial-contents  (LIST (c-pointer (POINT 1 2)) (c-pointer (POINT 3 4))))

...because my defclass is this:

(defclass std-vector-point ()
  ((c-pointer :reader c-pointer :initarg :c-pointer)))

Here is my function I need to change so a when it is run I can just enter (LIST (POINT 1 2) (POINT 3 4)) for the (first args) in the above mentioned conditional block and have the %c-arr-to-vector-point function be satisfied, because it accepts a list of pointers as its input.  But I need help because I don't want the user to see the c-pointer at all let alone have to wrap each (point i j) like this (c-pointer (point i j)) that is too much typing.  How would I do this without it making my function any slower.

(defun vector-point (&rest args)
  (cond
    ((fourth args)
     (error "odd number of args to VECTOR-POINT"))
    ((null (first args))
     (%vector-point))
    ((listp (first args))
     (%c-arr-to-vector-point (foreign-alloc :pointer :initial-contents (first args))))
    ((eq :size (second args))
     (%vector-point-size (first args)))
    ((and (eq (type-of (first args)) 'std-vector-point) (second args) (not (third args))) 
     (mem-aref (c-pointer 
        (%vector-point-to-c-array (first args))) :pointer (second args)))
    ((and (eq (type-of (first args)) 'std-vector-point) (second args) (third args)) 
     (mem-aref (c-pointer 
        (mem-aref (c-pointer 
               (%vector-point-to-c-array (first args))) :pointer (second args))) 
           :int (third args)))
    ((not (eq (type-of (first args)) 'std-vector-point))
     (error "The value ~a is not of type (STD-VECTOR-POINT)." (first args)))))
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