Made it easier to use `get-uncovered-expressions', fix use in checker.ss

svn: r5358

collects/handin-server/checker.ss

@@ -695,7 +695,7 @@
 
 (provide !all-covered)
 (define (!all-covered)
-  (let ([uncovered ((submission-eval) #f 'uncovered-expressions)])
+  (let ([uncovered (get-uncovered-expressions (submission-eval))])
     (cond [(pair? uncovered)
            (let ([stx (car uncovered)])
              (when stx

collects/handin-server/doc.txt

@@ -603,7 +603,8 @@ by this function.
 
 > get-uncovered-expressions
   A special value that, when passed to an evaluator created by
-  `make-evaluator', will return a list of uncovered syntax objects.
+  `make-evaluator' or applied on one, will return a list of uncovered
+  syntax objects.
 
 > namespace-specs
   A parameter that holds a list of values that specify how to create a

collects/handin-server/sandbox.ss

@@ -146,7 +146,7 @@
   (define make-eventspace    (mz/mr void make-eventspace))
   (define run-in-bg          (mz/mr thread queue-callback))
 
-  (define get-uncovered-expressions "get-uncovered-expressions")
+  (define (get-uncovered-expressions eval) (eval get-uncovered-expressions))
 
   (define (make-evaluator language teachpacks input-program)
     (let ([coverage-enabled (coverage-enabled)]