[WWcvs] pg: Disassemble Formula's properly when used with multiple variables in substitute(), etc.

[dpvc v. a. <we...@ma...>]

Log Message:
-----------
Disassemble Formula's properly when used with multiple variables in
substitute(), etc.  For example:

    $f->substitute(['x','y'] => Formula("xy,x^2-y^2"));

Modified Files:
--------------
    pg/lib:
        Parser.pm

Revision Data
-------------
Index: Parser.pm
===================================================================
RCS file: /webwork/cvs/system/pg/lib/Parser.pm,v
retrieving revision 1.47
retrieving revision 1.48
diff -Llib/Parser.pm -Llib/Parser.pm -u -r1.47 -r1.48
--- lib/Parser.pm
+++ lib/Parser.pm
@@ -736,7 +736,9 @@
   while (scalar(@_)) {
     $xref = shift; $value = shift;
     if (ref($xref) eq "ARRAY") {
-      $value = [@{$value->{data}}] if Value::isValue($value);
+      $value = Value::makeValue($value,context=>$context) unless ref($value);
+      $value = [$value->value] if Value::isValue($value);
+      $value = @{$value}[0,1] if Value::classMatch("Interval");
       $value = [$value] unless ref($value) eq 'ARRAY';
     } else {
       $xref = [$xref]; $value = [$value];