[Cffi-devel] Fw: What is the proper way to do GC in CFFI

[Joeish W]

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 at xs4all.nl> wrote:
 
Joeish W <joeish80829 at 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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>
>
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