Overrides the message set on the result object for failures in
$constraint. For example:
my $message = How hard is it to give me a number?;
my $constraint = Message($message, IsNumber);
my $result = $constraint->(duh...);
print $result->message, "\n";
The Message constraint overrides the error message returned by its
whole subtree, however, the Message specification nearest to the point
of failure will win. So while this
my $constraint = Message( Foo,
IsArrayRef( Message( Bar, IsInt )));
my $result = $constraint->([I am not an Integer]);
will print Bar, this
my $result = $constraint->(I\m not even an ArrayRef);
will output Foo.
Executes the passed $constraint in a newly generated scope named
SetResult($scope, CW$name, CW$constraint)
Stores the result ov an evaluation of $constraint in $scope under
Returns a true result if the result $name, which has to have been stored
previously in the scope named $scope, was valid.
Returns a true result.