add sys settrace usage.

Author: soarpenguin

call_trace.py

@@ -0,0 +1,66 @@
+#!/usr/bin/env python
+# encoding: utf-8
+
+import sys
+
+def trace_lines(frame, event, arg):
+    if event != 'line':
+        return
+    co = frame.f_code
+    func_name = co.co_name
+    line_no = frame.f_lineno
+    filename = co.co_filename
+    print '  %s line %s' % (func_name, line_no)
+
+def trace_calls(frame, event, arg):
+    if event != 'call':
+        return
+    co = frame.f_code
+    func_name = co.co_name
+    if func_name == 'write':
+        # Ignore write() calls from print statements
+        return
+    line_no = frame.f_lineno
+    filename = co.co_filename
+    print 'Call to %s on line %s of %s' % (func_name, line_no, filename)
+    if func_name in TRACE_INTO:
+        # Trace into this function
+        return trace_lines
+    return
+
+def trace_calls(frame, event, arg):
+    if event != 'call':
+        return
+    co = frame.f_code
+    func_name = co.co_name
+    if func_name == 'write':
+        # Ignore write() calls from print statements
+        return
+    func_line_no = frame.f_lineno
+    func_filename = co.co_filename
+    caller = frame.f_back
+    caller_line_no = caller.f_lineno
+    caller_filename = caller.f_code.co_filename
+    print 'Call to %s on line %s of %s from line %s of %s' % \
+        (func_name, func_line_no, func_filename,
+         caller_line_no, caller_filename)
+    return
+
+def trace_calls_and_returns(frame, event, arg):
+    co = frame.f_code
+    func_name = co.co_name
+    if func_name == 'write':
+        # Ignore write() calls from print statements
+        return
+    line_no = frame.f_lineno
+    filename = co.co_filename
+    if event == 'call':
+        print 'Call to %s on line %s of %s' % (func_name, line_no, filename)
+        return trace_calls_and_returns
+    elif event == 'return':
+        print '%s => %s' % (func_name, arg)
+    return
+
+''' settrace usage '''
+sys.settrace(trace_calls_and_returns)
+