Python in a Nutshell

Name

exc_info

Synopsis

exc_info( )

If the current thread is handling an exception, exc_info returns a tuple whose three items are the class, object, and traceback for the exception. If the current thread is not handling any exception, exc_info returns (None,None,None). A traceback object indirectly holds references to all variables of all functions that propagated the exception. Thus, if you hold a reference to the traceback object (for example, indirectly, by binding a variable to the whole tuple that exc_info returns), Python has to retain in memory data that might otherwise be garbage-collected. So you should make sure that any binding to the traceback object is of short duration. To ensure that the binding gets removed, you can use a try/finally statement (discussed in Chapter 6).