Make this lab program more useful for examining how trace functions work.

--HG--
rename : lab/trace_sample.py => lab/run_trace.py

1 files changed, 32 insertions, 0 deletions

diff --git a/lab/run_trace.py b/lab/run_trace.py
new file mode 100644
index 00000000..3822a804
--- /dev/null
+++ b/lab/run_trace.py
@@ -0,0 +1,32 @@
+"""Run a simple trace function on a file of Python code."""
+
+import os, sys
+
+nest = 0
+
+def trace(frame, event, arg):
+    global nest
+
+    if nest is None:
+        # This can happen when Python is shutting down.
+        return None
+
+    print "%s%s %s %d @%d" % (
+        "    " * nest,
+        event,
+        os.path.basename(frame.f_code.co_filename),
+        frame.f_lineno,
+        frame.f_lasti,
+        )
+
+    if event == 'call':
+        nest += 1
+    if event == 'return':
+        nest -= 1
+
+    return trace
+
+the_program = sys.argv[1]
+
+sys.settrace(trace)
+execfile(the_program)