Got rid of answer signatures - these don't work with approximate answers at all.…

Got rid of answer signatures - these don't work with approximate answers at all.  Instead, implemented comparison-based hint matching.

Tests are broken, hint manager is probably broken.

common/lib/capa/capa/responsetypes.py

@@ -917,6 +917,27 @@ class NumericalResponse(LoncapaResponse):
 
     # TODO: add check_hint_condition(self, hxml_set, student_answers)
 
+    def answer_compare(self, a, b):
+        """
+        Outside-facing function that lets us compare two numerical answers,
+        with this problem's tolerance.
+        """
+        return compare_with_tolerance(
+            evaluator(dict(), dict(), a),
+            evaluator(dict(), dict(), b),
+            self.tolerance
+        )
+
+    def validate_answer(self, answer):
+        """
+        Returns whether this answer is in a valid form.
+        """
+        try:
+            evaluator(dict(), dict(), answer)
+            return True
+        except StudentInputError:
+            return False
+
     def get_answers(self):
         return {self.answer_id: self.correct_answer}
 
@@ -1858,6 +1879,24 @@ class FormulaResponse(LoncapaResponse):
                 return "incorrect"
         return "correct"
 
+    def answer_compare(self, a, b):
+        """
+        An external interface for comparing whether a and b are equal.
+        """
+        internal_result = self.check_formula(a, b, self.samples)
+        return internal_result == "correct"
+
+    def validate_answer(self, answer):
+        """
+        Returns whether this answer is in a valid form.
+        """
+        var_dict_list = self.randomize_variables(self.samples)
+        try:
+            self.hash_answers(answer, var_dict_list)
+            return True
+        except StudentInputError:
+            return False
+
     def strip_dict(self, d):
         ''' Takes a dict. Returns an identical dict, with all non-word
         keys and all non-numeric values stripped out. All values also

common/templates/hinter_display.html

@@ -3,18 +3,14 @@
 
 
 <%def name="get_hint()">
-    % if best_hint != '':
+    % if len(hints) > 0:
         <h4> Hints from students who made similar mistakes: </h4>
         <ul>
-        <li> ${best_hint} </li>
-    % endif
-    % if rand_hint_1 != '':
-        <li> ${rand_hint_1} </li>
-    % endif
-    % if rand_hint_2 != '':
-        <li> ${rand_hint_2} </li>
+        % for hint in hints:
+            <li> ${hint} </li>
+        % endfor
+        </ul>
     % endif
-    </ul>
 </%def>
 
 <%def name="get_feedback()">
@@ -66,17 +62,13 @@
 
     <div id="answer-tabs">
         <ul>
-        % for answer in answer_to_hints:
+        % for answer in user_submissions:
             <li><a href="#previous-answer-${unspace(answer)}"> ${answer} </a></li>
         % endfor
         </ul>
 
-        % for answer, pk_dict in answer_to_hints.items():
-            <%
-                import json
-                all_pks = json.dumps(pk_dict.keys())
-            %>
-            <div class = "previous-answer" id="previous-answer-${unspace(answer)}" data-answer="${answer}" data-all-pks='${all_pks}'>
+        % for answer in user_submissions:
+            <div class = "previous-answer" id="previous-answer-${unspace(answer)}" data-answer="${answer}">
             <div class = "hint-inner-container">
                 <p>
                 What hint would you give a student who made the same mistake you did?  Please don't give away the answer.