[Python-3000] Exceptions internals and removing sys.exc_*

[Giovanni Bajo]

On 21/01/2007 20.50, Tony Lownds wrote:

> What's the cost of keeping sys.exc_info() on 3.0? If that cost is a  
> hindrance on 3.0, then
> fine, sys.exc_info() and the ability for module authors to use a  
> single codebase on 2.x and
> 3.0 can be given up.

It's been stated many times that making it possible to have a single codebase 
for both 2.x and 3.0 is *not* a goal of the Python 3.0 project.

What it is more likely to happen is that it will be possible to maintain a 
codebase which runs under 2.x and can be automatically converted to a 
3.0-compatible codebase. This will be possible through some (all?) of the 
following utilities (nothing is set in stone at this point):

- A "-3" command line option in Python 2.x which turns on DeprecationWarnings 
on any construct that will go away in 3.x
- A "from __future__ import py3k" to activate special Py3k constructs (like 
new keywords) in 2.x.
- The addition of Py3k "features" to Python 2.x, in the cases where it does 
not hinder 2.x maintenance too much (eg: new names for modules/packages in 
stdlib).
- The 2to3 refactoring tool: a program to automatically convert Python 2.x 
source code to Python 3.x source code (an initial version is already available 
in the sandbox).
-- 
Giovanni Bajo