improve stringification of elements in NumMatrix2D to follow best-pra…

…ctices and be more compatible with the get_string vtables of other matrix types. Fix string tests for the type to match the new behavior

src/pmc/nummatrix2d.pmc

@@ -321,8 +321,7 @@ elements.
 
     VTABLE STRING * get_string_keyed(PMC * key) {
         const FLOATVAL f = VTABLE_get_number_keyed(INTERP, SELF, key);
-        STRING * const item = Parrot_sprintf_c(INTERP, "%f", f);
-        return item;
+        return Parrot_str_from_num(INTERP, f);
     }
 
     VTABLE PMC * get_pmc_keyed(PMC * key) {
@@ -375,8 +374,7 @@ Nth number. The array is arranged in memory row by row.
 
     VTABLE STRING * get_string_keyed_int(INTVAL key) {
         const FLOATVAL f = VTABLE_get_number_keyed_int(INTERP, SELF, key);
-        STRING * const item = Parrot_sprintf_c(INTERP, "%f", f);
-        return item;
+        return Parrot_str_from_num(INTERP, f);
     }
 
     VTABLE PMC * get_pmc_keyed_int(INTVAL key) {
@@ -444,6 +442,7 @@ Get a string representation of the matrix.
         INTVAL i, j;
         PMC * const builder = Parrot_pmc_new(INTERP, enum_class_StringBuilder);
         STRING * const newline = Parrot_str_new(INTERP, "\n", 1);
+        STRING * const tab = Parrot_str_new(INTERP, "\t", 1);
         FLOATVAL * const s = attrs->storage;
         const INTVAL rows = attrs->rows;
         const INTVAL cols = attrs->cols;
@@ -452,7 +451,8 @@ Get a string representation of the matrix.
         for (i = 0; i < rows; ++i) {
             for (j = 0; j < cols; ++j) {
                 const FLOATVAL f = ITEM_XY(s, flags, rows, cols, i, j);
-                STRING * const item = Parrot_sprintf_c(INTERP, "\t%f", f);
+                STRING * const item = Parrot_str_from_num(INTERP, f);
+                VTABLE_push_string(INTERP, builder, tab);
                 VTABLE_push_string(INTERP, builder, item);
             }
             VTABLE_push_string(INTERP, builder, newline);

t/pmc/nummatrix2d.t

@@ -35,10 +35,13 @@ method test_VTABLE_get_string() {
     my $m := self.matrix2x2(1.0, 2.0,
                             3.0, 4.0);
     my $s := pir::set__SP($m);
-    my $t := pir::sprintf__SSP("\t%f\t%f\n\t%f\t%f\n", [1.0, 2.0, 3.0, 4.0]);
+    my $t := pir::sprintf__SSP("\t%S\t%S\n\t%S\t%S\n", [1.0, 2.0, 3.0, 4.0]);
     assert_equal($s, $t, "cannot get string");
 }
 
+# TODO: Tests for get/set_pmc to prove that we get a Float from it
+#             $P1 = $P0[0]
+#            assert_instance_of($P1, "Float", "got Number PMC from linear index")
 
 # Addition Tests
 
@@ -59,7 +62,6 @@ method test_VTABLE_add_NUMMATRIX2D_SIZEFAIL() {
     });
 }
 
-
 method test_VTABLE_i_add_NUMMATRIX2D() {
     my $m := self.matrix2x2(1.0, 3.0, 2.0, 4.0);
     my $n := self.matrix2x2(5.0, 7.0, 6.0, 8.0);
@@ -73,7 +75,6 @@ method test_VTABLE_i_add_NUMMATRIX2D() {
     }
 }
 
-
 # Subtraction Tests
 
 method test_VTABLE_subtract_NUMMATRIX2D() {
@@ -107,7 +108,6 @@ method test_VTABLE_i_subtract_NUMMATRIX2D() {
     }
 }
 
-
 # Multiplication Tests
 
 method test_VTABLE_multiply_NUMMATRIX2D() {
@@ -158,7 +158,6 @@ method test_VTABLE_i_multiply_NUMMATRIX2D() {
     }
 }
 
-
 # Block Get/Set method tests
 
 method test_METHOD_set_block() {