The bdb Module

The bdb module provides a framework for debuggers. You can use this to create your own custom debuggers, as Example 11-3 shows.

To implement custom behavior, subclass the Bdb class, and override the user methods (which are called whenever the debugger stops). To control the debugger, use the various set methods.

Example 11-3. Using the bdb Mdule

File: bdb-example-1.py import bdb import time def spam(n): j = 0 for i in range(n): j = j + i return n def egg(n): spam(n) spam(n) spam(n) spam(n) def test(n): egg(n) class myDebugger(bdb.Bdb): run = 0 def user_call(self, frame, args): name = frame.f_code.co_name or "" print "call", name, args self.set_continue() # continue def user_line(self, frame): if self.run: self.run = 0 self.set_trace() # start tracing else: # arrived at breakpoint name = frame.f_code.co_name or "" filename = self.canonic(frame.f_code.co_filename) print "break at", filename, frame.f_lineno, "in", name print "continue..." self.set_continue() # continue to next breakpoint def user_return(self, frame, value): name = frame.f_code.co_name or "" print "return from", name, value print "continue..." self.set_continue() # continue def user_exception(self, frame, exception): name = frame.f_code.co_name or "" print "exception in", name, exception print "continue..." self.set_continue() # continue db = myDebugger() db.run = 1 db.set_break("bdb-example-1.py", 7) db.runcall(test, 1) continue... call egg None call spam None break at C:ematterlibrarybookdb-example-1.py 7 in spam continue... call spam None break at C:ematterlibrarybookdb-example-1.py 7 in spam continue... call spam None break at C:ematterlibrarybookdb-example-1.py 7 in spam continue... call spam None break at C:ematterlibrarybookdb-example-1.py 7 in spam continue...