Yikes: when using the Python tracing function, we haven't been caching the results of should_trace since <<changeset a480f40d1fa4>>

2 files changed, 9 insertions, 3 deletions

diff --git a/TODO.txt b/TODO.txt
index b45c2c87..d2cf8d37 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -1,9 +1,12 @@
 Coverage TODO
 
 * Cleanups discovered while doing --source:
-    - PyTracer doesn't use should_trace_cache!!
+    + PyTracer doesn't use should_trace_cache!!
     - optparse recommends using make_option, not Option constructor
-
+* --source stuff:
+    - warn if a package is never found.
+    - warn if no data was collected
+    - tie --source into reporting
 
 * plugin work
     + add --cover-include.
diff --git a/coverage/collector.py b/coverage/collector.py
index 06ccda7e..55211f2a 100644
--- a/coverage/collector.py
+++ b/coverage/collector.py
@@ -60,7 +60,10 @@ class PyTracer(object):
             # in this file.
             self.data_stack.append((self.cur_file_data, self.last_line))
             filename = frame.f_code.co_filename
-            tracename = self.should_trace(filename, frame)
+            tracename = self.should_trace_cache.get(filename)
+            if tracename is None:
+                tracename = self.should_trace(filename, frame)
+                self.should_trace_cache[filename] = tracename
             if tracename:
                 if tracename not in self.data:
                     self.data[tracename] = {}