From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-05-17T07:40:31+09:00
Subject: rb_gc_mark question



i reading some code attm that goes:

   static VALUE convertgslmatrixToRubyMatrix(gsl_matrix *dm)
   {
     int i, j;
     volatile VALUE result;
     assert(dm);
   //  printf("Trying to convert dm %p\n", dm);
   //    printf("With size %d, %d\n", dm->size1, dm->size2);
     volatile VALUE rows = rb_ary_new();
     rb_gc_mark(rows);
     for (i = 0; i < dm->size1; i += 1) {
       volatile VALUE currow = rb_ary_new();
       rb_gc_mark(currow);
       rb_ary_push(rows, currow);
       for (j = 0; j < dm->size2; j += 1) {
         double val = gsl_matrix_get(dm, i, j);
         VALUE rval = rb_float_new(val);
         rb_gc_mark(rval);
         rb_ary_push(currow, rval);
       }
     }
     result = rb_funcall(cMatrix, rb_intern("rows"), 2, rows, Qnil);
     rb_gc_mark(result);
     return result;
   }


now, everything i know says this should be something along the lines of:

   static VALUE
   convertgslmatrixToRubyMatrix (gsl_matrix * dm)
   {
     int i, j;
     VALUE result;
     VALUE rows = rb_ary_new ();
     for (i = 0; i < dm->size1; i += 1)
       {
         VALUE currow = rb_ary_new ();
         rb_gc_mark (currow);
         rb_ary_push (rows, currow);
         for (j = 0; j < dm->size2; j += 1)
           {
             double val = gsl_matrix_get (dm, i, j);
             VALUE rval = rb_float_new (val);
             rb_ary_push (currow, rval);
           }
       }
     result = rb_funcall (cMatrix, rb_intern ("rows"), 2, rows, Qnil);
     return result;
   }

(please correct me if i'm wrong)

or nasty things will happen in memory right?  what would it do to call
rb_gc_mark on ruby objects like this?

cheers.

-a
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