backwards-compatibility

[Terry Reedy]

On 2/26/2011 11:32 AM, Benjamin Kaplan wrote:
> On Sat, Feb 26, 2011 at 8:11 AM, Jason Swails<jason.swails at gmail.com>  wrote:
>> Hello,
>>
>> I have a question I was having a difficult time finding with a quick google
>> search, so I figured someone on here might know.  For the sake of backwards
>> compatibility (and supporting systems whose default python is OLD), I'd like
>> to rewrite some code to be compliant with Pythons as old as 2.4.  For this
>> reason I've already had to do away with all "{1}".format(item), but I'm
>> running into new problems with the packages I've written.  For instance, I
>> have a package "package1" with "subpackage1".  One of the modules in
>> subpackage1 imports the exceptions module from package1, and I do that like
>> this:
>>
>> from ..exceptions import MyException
>>
>
> You'll have to import that using the absolute import. It would be
> "from package1.exceptions import MyException".
>
>> Which is perfectly fine by python2.5, 2.6, and 2.7; but unacceptable in
>> python2.4.  Any thoughts?
>>
>> Another python2.6 feature I'm using is
>>
>> except Exception as err:
>>     print err
>>
>
> except Exception, err :

Of course, this breaks compatibility with 3.x without running through 
2to3. You did not specify how far forward you want to cater to.

-- 
Terry Jan Reedy