Question

try:
    raise TypeError
except TypeError:
    try:
        tb = sys.exc_info()[2]
        TracebackType = type(tb)
        FrameType = type(tb.tb_frame)
    except AttributeError:
        # In the restricted environment, exc_info returns (None, None,
        # None) Then, tb.tb_frame gives an attribute error
        pass
    tb = None; del tb

I can’t understand this code at all. What is it’s purpose?

Answer 1

It’s a trick to get a traceback object and a frame object so that TracebackType and FrameType can be assigned their types. It simply raises an exception so it can catch the exception, then get the traceback and frame from sys.exc_info.