程序跟踪装饰器，用于程序运行的时候打印出每一步的运行顺序和调用逻辑

Decorator-Trace.py

import sys,os,linecache 
def trace(f): 
    def globaltrace(frame, why, arg): 
        if why == "call": 
            return localtrace 
        return None 
    def localtrace(frame, why, arg): 
        if why == "line": 
            # record the file name and line number of every trace 
            filename = frame.f_code.co_filename 
            lineno = frame.f_lineno
            bname = os.path.basename(filename) 
            print "{}({}): {}".format( bname, lineno, linecache.getline(filename, lineno).strip('\r\n')), 
        return localtrace 
    def _f(*args, **kwds): 
        sys.settrace(globaltrace) 
        result = f(*args, **kwds) sys.settrace(None) 
        return result 
    return _f