[Cffi-devel] Help perfecting my GC finalizer/constructor

[Joeish W]

Thanks for your replies to my question, I was planning to go the trivial-garbage route and someone from CFFI-DEVEL kindly gave me this code to do GC automatically using my mat and del-mat functions

 (defstruct (cvmatrix (:constructor %make-cvmatrix))
  (sap (mat) :type sb-sys:system-area-pointer :read-only t))

 (defun make-cvmatrix ()
  (let* ((matrix (%make-cvmatrix))
          (sap (cvmatrix-sap matrix)))
    (tg:finalize matrix (lambda (x) (del-mat sap)))
    matrix))

When I run the make-cvmatrix function to create a matrix  it outputs a struct instead of a pointer like i needed. I changed the last line of the make-cvmatrix function to be "sap"  as below:

    (tg:finalize matrix (lambda (x) (del-mat sap)))
    sap))

...and it appears to run poorly with only major variations in my ram levels which i suppose is just a result of lisps GC in process.
Since I'm new to GC w/ trivial-garbage, I was hoping someone can verify first that the change to sap was an ok move. 

I was hoping someone could edit my code so I have a good example of Lisp GC with TG to work from and if I write a defcfun for this C wrapper :

Mat* cv_create_Mat_typed(int rows, int cols, int type) {
    return new Mat(rows, cols, type);
}

eg:


(defcfun ("cv_create_Mat_typed" mat-typed)  (:pointer mat)
  "MAT constructor with a row, column and type parameter."
  (rows :int)
  (cols :int)
  (type :int))

show me where the rows cols type params get placed in an edited finalizer/constructor above..I would definately appreciate greatly:), concrete examples using the code I posted.
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