This is a follow up on my posted fix to copy-to.  For some reason this has triggered another
error.  I do not understand how that other error is triggered.  The error and the fix are discussed
at the bottom of the email

On Fri, Jan 4, 2013 at 10:39 AM, Mirko Vukovic <mirko.vukovic@gmail.com> wrote:

The following works in sbcl+grid:

(copy-to (make-array 2 :element-type 'double-float :initial-contents '(1.0d0 2.0d0)) 'grid:foreign-array)

But it does not work in clisp+grid.

The root cause lies in the function grid/array.lisp/element-type.  It uses `(array-element-type grid)'.

But this can present a problem.  Quoting hyperspec:

(Because of array upgrading, this type specifier can in some cases denote a supertype of the expressed array element type of the array.)

In CLISP, array-element-type returns `T' when passed #(1d0 2d0)

It returns T even when passed a simple array:

(array-element-type (make-array 2 :element-type 'double-float :initial-contents
                      '(1.0d0 2.0d0)
                      :adjustable nil
                      :fill-pointer nil
                      :displaced-to nil) )

The proposed fix is

(defmethod element-type ((grid array))
  (type-of (row-major-aref grid 0))
  #+skip(array-element-type grid))

Now copy-to works in clisp as well.

Mirko

After finishing this, I recompiled afresh, and got another error that I traced to make-grid-data and make-array

In clisp, make-array will return an array of NIL's even if the element-type is specified as double float.  In SBCL make-array
will return an array filled with 1d0.

I had to add some clisp specific code to make-grid-data in order for it to initialize properly.

First, a helper function:
(defun default-element (element-type)
   "Return a default element depending on element-type
"
   (let ((a-list '((double-float . 1d0)
           (symbol . T))))
     (let ((match (cdr (assoc element-type a-list))))
       (assert match ()
           "Default element type undefined for element-type ~a"
           element-type)
       match)))

And second, a bit of set-up code in make-grid-data.  I broke apart the (let* statement
to provide an explicit initial element if it has not been specified already:

(defmethod make-grid-data
  ((type (eql 'array)) dimensions rest-spec
   &key (initial-element nil initial-element-p)
   (initial-contents nil initial-contents-p))
  (let ((element-type (top-spec-type rest-spec)))
    #+clisp
    (unless (or initial-element-p
        initial-contents-p)
      (setf initial-element (default-element element-type)
        initial-element-p t))
    (let ((array ... UNCHANGED


Summary:  To fix to copy-to, I modified (defmethod element-type ((grid array))
For some unknown reason, that triggered an error in the array initialization routine.
To fix that, I had to add code to make-grid-data, so that it fills double-float arrays with 0d0
instead of NIL's

I will continue using this code to see if there are additional problems. 

BTW, I realize that CLISP is not a preferred platform for speedy computation, but that is what I use
on Windows, until SBCL gets officially ported to it.  And in addition, it is a nice cross-check on portability.

Mirko



_______________________________________________
GSLL-devel mailing list
GSLL-devel@common-lisp.net
http://lists.common-lisp.net/cgi-bin/mailman/listinfo/gsll-devel