python debug open_files

import __builtin__
openfiles = set()
oldfile = __builtin__.file
class newfile(oldfile):
    def __init__(self, *args, **kwargs):
        self.x = args[0]
        print "### OPENING %s ###" % str(self.x)            
        oldfile.__init__(self, *args, **kwargs)
        openfiles.add(self)

    def close(self):
        print "### CLOSING %s ###" % str(self.x)
        oldfile.close(self)
        openfiles.remove(self)
oldopen = __builtin__.open
def newopen(*args):
    return newfile(*args, **kwargs)
__builtin__.file = newfile
__builtin__.open = newopen

def printOpenFiles():
    print "### %d OPEN FILES: [%s]" % (len(openfiles), ", ".join(f.x for f in openfiles))