[Zope-dev] ZPT backward compatibility

[Jim Fulton]

Andreas Jung wrote:
> 
> 
> --On 16. Januar 2006 13:08:31 -0500 Jim Fulton <jim at zope.com> wrote:
> 
>> I'll just note that:
>>
>> - I agree with your point about deprecation warnings.  IOW
>>    we should not check in new deprecation warnings on the trunk
>>    that cause warnings to be output when running the standard tests.
>>    We should correct any code that needs to be updated first.
>>    (Personally, I add the deprecation warning, making sure that I
>>    get the expected warnings, and then I make the warnings go away.)
> 
> 
> But you can only correct code when you have a reasonable replacement. In 
> case we should use my current ZPT replacement based on the Z3 
> implementation we would deprecate lib/python/TALES and have deprecation 
> warnings for two major releases. But we can't replace lib/python/TALES 
> with the Z3 tal|tales
> packages since we can expect incompatibilities which are not acceptable 
> for backward compatibility issues. One could write fascades for such 
> modules (Philipp already wrote one for STX) but I doubt that they will 
> be 100% compatible. I would prefer to keep such modules in place and to 
> just remove them after the deprecation period.

There are two separate issues here:

1. ZPT backward compatibility.

    Are we introdcuting ZPT backward incompatibilities? (Aside from module
    paths)?  If so, then I think we need to have a proposal. (Maybe you already
    made one and I wasn't paying attention.  I don't see one at:
    http://www.zope.org/Wikis/DevSite/Proposals/FrontPage.

2. If we decide to change something, even if it's backward incompatible,
    we need to change Zope itself to do things the new way before we expect
    other people to and before we introduce the deprecation warning.
    If there isn't a valid new way of doing something, then we can't deprecate
    the old way.

Jim

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