[Python-Dev] Py2.5 release schedule

Barry Warsaw barry at python.org
Sun Jul 30 21:44:08 CEST 2006


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Re: Python 2.5 compatibility

On Jul 28, 2006, at 8:57 AM, Barry Warsaw wrote:

> +1.  It would give me more type to port and test a few of my  
> applications to the new version.
>
> I'm still working on Mailman but the most painful thing so far has  
> been the conversion of exceptions to new-style classes, and even  
> that wasn't /too/ painful.

I believe I've finished porting Mailman to Python 2.5.  None of the  
issues were insurmountable, but here they are FTR:

1) Exceptions are new-style classes but Mailman was doing one  
specific test against the type of an object to see if it needed to be  
instantiated.  This test was written as:

if isinstance(obj, ClassType)

which fails in Python 2.5.  I actually rewrote it like so:

if isinstance(obj, ClassType) or isinstance(obj, type(type))

in MM2.1 because it has to be backward compatible to Python 2.1.

2) There was one place where I was commonly raising a string and that  
generates deprecation warnings, so I changed that to a class.  There  
are a few other legacy string exceptions defined in the code, but  
they are rarely used and should all get rewritten as well.

3) Cookie.py's repr changed so that trailing semicolons are no longer  
output on the end of text lines.  I understand this change was made  
so that Python cookies were more RFC compliant, but it broke some  
homegrown cookie text splitting we were doing.  I changed this code  
to split on lines first.

All in all, not too bad although the Cookie.py change took a while to  
track down!

- -Barry

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