[WWcvs] pg: Added a new flag that controls how a list with a single entry that

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

Log Message:
-----------
Added a new flag that controls how a list with a single entry that is
a list is handled.  In the past, the student could not specify such an
item, but now the default is to form a list with a single entry that
is a list, provided the student has used parens explicitly around his
list.  So "1,2" will be a list with two items and "(1,2)" will be a
list with one item (a list).  This improves the ability to use the
list checker for lists of arbitrary pairs (like "(1,max)") especially
when you want to check for lists of these (e.g., "(1,max),(2,min)"),
since otherwise a single pair "(1,max)" entered by the student would
become the list "1,max" rather than the list containing the single
pair.

If you really want "(1,max)" to become the list "1,max", use

   List("1,max")->cmp(implicitList=>0);

to prevent single lists from forming a list of a single item.

Modified Files:
--------------
    pg/lib/Value:
        AnswerChecker.pm

Revision Data
-------------
Index: AnswerChecker.pm
===================================================================
RCS file: /webwork/cvs/system/pg/lib/Value/AnswerChecker.pm,v
retrieving revision 1.74
retrieving revision 1.75
diff -Llib/Value/AnswerChecker.pm -Llib/Value/AnswerChecker.pm -u -r1.74 -r1.75
--- lib/Value/AnswerChecker.pm
+++ lib/Value/AnswerChecker.pm
@@ -1012,6 +1012,7 @@
     extra => undef,
     requireParenMatch => 1,
     removeParens => 1,
+    implicitList => 1,
   );
 }
 
@@ -1047,6 +1048,7 @@
   my $showParenHints    = getOption($ans,'showParenHints');
   my $partialCredit     = getOption($ans,'partialCredit');
   my $requireParenMatch = $ans->{requireParenMatch};
+  my $implicitList      = $ans->{implicitList};
   my $typeMatch         = $ans->{typeMatch};
   my $value             = $ans->{entry_type};
   my $ltype             = $ans->{list_type} || lc($self->type);
@@ -1074,11 +1076,19 @@
   my $student = $ans->{student_value}; my @student = ($student);
   my ($sOpen,$sClose) = ('','');
   if (Value::isFormula($student) && $student->type eq $self->type) {
-    @student = Value::List->splitFormula($student,$ans);
-    $sOpen = $student->{tree}{open}; $sClose = $student->{tree}{close};
+    if ($implicitList && $student->{tree}{open} ne '') {
+      @student = ($student);
+    } else {
+      @student = Value::List->splitFormula($student,$ans);
+      $sOpen = $student->{tree}{open}; $sClose = $student->{tree}{close};
+    }
   } elsif ($student->class ne 'Formula' && $student->class eq $self->type) {
-    @student = @{$student->{data}};
-    $sOpen = $student->{open}; $sClose = $student->{close};
+    if ($implicitList && $student->{open} ne '') {
+      @student = ($student);
+    } else {
+      @student = @{$student->{data}};
+      $sOpen = $student->{open}; $sClose = $student->{close};
+    }
   }
   return if $ans->{split_error};
   #