I already figured out a great finalizer, I could just use help on one thing.
The below finalizer is for the %mat defcfun below that.
How do I update the finalizer below to be for the mat-data defcfun at the
bottom of the page. So where do I put the rows cols params, there seems
to be no place for them in the defstruct wwhere %mat is called. Any
help is appreciated
 
 
 
(defstruct (cvmatrix (:constructor %make-cvmatrix))
  (sap (%mat) :type sb-sys:system-area-pointer :read-only t))
 
 (defun make-cvmatrix (&optional enable-finalizer)
  (let* ((matrix (%make-cvmatrix))
          (sap (cvmatrix-sap matrix)))
(when enable-finalizer
    (tg:finalize matrix (lambda () (del-mat sap))))
    sap))

 
(defcfun ("cv_create_Mat" %mat) (:pointer mat)
  "MAT constructor")
 
;; Mat::Mat(int rows, int cols, int type, void* data) 
;; Mat* cv_create_Mat_with_data(int rows, int cols, int type, void* data)
(defcfun ("cv_create_Mat_with_data" mat-data) (:pointer mat)
  (rows :int)
  (cols :int)
  (type :int)
  (data :pointer))
On Sunday, April 13, 2014 12:28 AM, Willem Rein Oudshoorn <woudshoo@xs4all.nl> wrote:
Joeish W <joeish80829@yahoo.com> writes:

> I have Lisp functions that wrap C wrappers for C++ functions that
> contain a new operator. The C wrappers have to stay the same I can't
> change those but I was advised to update my method of GC.

As already mentioned before, use the package 'trivial-garbage'.

The cl-git package that wraps the libgit2 C code might be a good
example. 

The cl-git code tries the handle automatic freeing by the garbage
collector, but also allows you to free manually. 
In addition it keeps track of dependencies, e.g. in cl-git
a 'commit' is only valid as long as the 'repository' is open.

It is not much code and might give some inspiration. 

Disclaimer, I was quite involved in this bit of cl-git, the
project is on github:

https://github.com/russell/cl-git


As an additional question, maybe not well suited for this list.
I see you are wrapping the OpenCV code.  There are already two
other wrappers.  So I am curious what are the deficiencies of the
existing wrappers that your wrapper tries to solve?

Wim Oudshoorn.


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