How can I raise an Exception that includes a Unicode string?

Question

I'm writing Python 2 code with Unicode strings, importing unicode_literals and I'm having issues with raising exceptions.

# -*- coding: utf-8 -*-

from __future__ import unicode_literals

raise Exception('Tést')

When doing this, the 'Tést' string is stripped off the terminal.

I can workaround this with

raise Exception('Tést'.encode('utf-8'))

I'd rather find a global solution than having to do this in all raise Exception statements.

(Since I'm using PyQt's tr() function in Exception messages, special characters must be handled, I can't know at coding time whether encode('utf-8') is necessary.)

Worse. Sometimes, I want to catch an Exception, get its message, and raise a new Exception, concatenating a base string with the first Exception string.

I have to do it this way:

try:
    raise TypeError('Tést'.encode('utf-8'))
except Exception as e:
    raise Exception('Exception: {}'.format(str(e).decode('utf-8')).encode('utf-8'))

but I really wish it could be less cumbersome (and this example doesn't even include the self.tr() calls).

Is there any simpler way ?

(And as a side question, are things simpler with Python3 ? Can Exception use unicode strings ?)

Answer 1

Thanks to the comments below the question, I came up with this.

The idea is to use a custom Exception subclass.

# -*- coding: utf-8 -*-

from __future__ import unicode_literals

class MyException(Exception):

    def __init__(self, message):

        if isinstance(message, unicode):
            super(MyException, self).__init__(message.encode('utf-8'))
            self.message = message

        elif isinstance(message, str):
            super(MyException, self).__init__(message)
            self.message = message.decode('utf-8')

        # This shouldn't happen...
        else:
            raise TypeError

    def __unicode__(self):

        return self.message

class MySubException(MyException):
    pass

try:
    raise MyException('Tést')
except MyException as e:
    print(e.message)
    raise MySubException('SubException: {}'.format(e))