update change log; fix print usage; more comments

doc/changes.rst

@@ -5,9 +5,10 @@ Change Log
 3.0.4 (unreleased)
 ------------------
 
-* Add `Timer` class to standardize timing reports (PR `#151`_).
+* Add `Timer` class to standardize timing reports (PRs `#151`_, `#152`_).
 
 .. _`#151`: https://github.com/desihub/desiutil/pull/151
+.. _`#152`: https://github.com/desihub/desiutil/pull/152
 
 3.0.3 (2020-08-04)
 ------------------

py/desiutil/test/test_timer.py

@@ -125,7 +125,12 @@ def test_parsetime(self):
 
     @unittest.skipUnless(dateutil_installed, "dateutil not installed")
     def test_parsetime_dateutil(self):
-        """If dateutil installed, test fancy date string parsing"""
+        """If dateutil installed, test ISO-8601 date string parsing
+
+        Fancier "Tue Sep 22 13:42:26 PDT 2020" parsing may or may not
+        work depending upon timezone knowledge of host machine; not
+        tested or supported for now, but may be re-added later if needed.
+        """
         # t0 = parsetime("Tue Sep 22 13:42:26 PDT 2020")
         # self.assertAlmostEqual(t0, 1600807346.0)
         t1 = parsetime("2020-09-22T13:42:26-07:00")

py/desiutil/timer.py

@@ -186,10 +186,10 @@ def cancel(self, name):
         isotime = datetime.datetime.fromtimestamp(t1).isoformat()
         if name in self.timers:
             dt = t1 - self.timers[name]['start']
-            print(self._prefix('CANCEL'), f'Canceling timer {name} at {isotime} after {dt:.2f} seconds')
+            self._print('CANCEL', f'Canceling timer {name} at {isotime} after {dt:.2f} seconds')
             del self.timers[name]
         else:
-            print(self._prefix('WARNING'), f'Attempt to cancel non-existent timer {name} at {isotime}')
+            self._print('WARNING', f'Attempt to cancel non-existent timer {name} at {isotime}')
 
     @contextmanager
     def time(self, name):