[C++-sig] Strange about the C++ exception in Python

[Grant]

Hi,

We have exception classees which is inherited from std::exception class. I 
implemented the what() function always return the exception class's name and 
description string. When the exception is throwed in C++ code, python 
interpreter could catch it as RuntimeError. Then I print out the first word 
of this RuntimeError object's args[0], it should be the c++ exception 
class's name.

Now the problem is this method works some times. Since I put try/except in 
the unit test phrase, compare the exception name with a string. Some times 
it works fine, but sometimes exception name is just ''. I don't understand 
why it work the way so randomly.

I use unittest module and test_support of test module for my unit test 
framework. Does it have anything with the unit test, or it's a boost.python 
issue, or the Python interpreter just misses to catch c++ exception 
sometime?

I tried to use boost.python's translator, but it does not help.

How do you guys handle the exception throwed in C++?

Thanks for your suggestion,
Grant