question on Bdb???

[BruceKL WhoH]

Hi ,all
    recently I'm trying to write a vim script to integrate python debugger in to vim so that I can debugger python script in vim. But I come across a question.
    First I need to write a derived class of Bdb, so I must override the user_* methods.but how can I return to vim? When user_* is called , it should return to vim, and when the user 'step' or 'next', it return to the user_* call again, and run. But how to achieve this?
    It's apparently I need to 'freeze' the Bdb and wait for some input coming from vim ,and then go back to the right place. but we can't make vim functions as callbacks. That's the question.
    maybe iterator/generator can be used to solve it. But I don't know how.
    Any one can help me?
    Any suggestions are appreciated.
	

　　　　　　　　BruceKL WhoH
　　　　　　　　BruceWhoHKL at gawab.com
　　　　　　　　　　2004-05-13