[Typo3-dev] RFC: new condition ORIG_TYPO3_VERSION - call for volunteers

[Michael Stucki]

Sebastian Kurfuerst wrote:

> @Johannes, I think you are right in general, but TYPO3 has been known
> for its great upgradability - and we'll definitely try to continue like
> this - as that's as well why web agencys chose us and not other
> products. From a developer's point of view it is always easy to say
> "let's just drop it and do it right" - but we won't make life easier for
> people _using_ TYPO3.

About backwards compatibility:

I see a lot of different kinds of BC:
- API stability (don't change the base classes/function)
- Syntax stability (don't change any Typoscript properties)
- Visual backwards compatibility (don't change the website output)
- System stability (don't change database structure, etc.)

There may be more.

TYPO3 gives a high respect to all of the above compatibilities, but not all
of them are equally easy to break:

About API stability:
Currently I see no problems with this. Functions that have been changed have
been turned into a workaround-wrapper, and the function is now marked as
"deprecated".
Maybe it could be a good help to write a little tool that lists all calls to
deprecated functions, so then we can do some cleanup if we announce it
early enough...


About Syntax stability:
Here I think the version condition would be a good solution. Something
similar is also used by Debians debhelper tools, so it seems it must be a
good solution! :-)
There's just one thing: I think the name of the condition should be changed
as it does not neccessarily relate with a TYPO3 version. Suggestion (like
debhelpers "DH_COMPAT") would be "TS_COMPAT". This makes it clear that the
setting does not relate with the TYPO3 version and the compat switch could
be extended to extensions as well:
You can change everything that you know it needs to be changed, then you
update the TS_COMPAT mode although the TYPO3 version stays the same. Will
work fine since the compat value will never descrease...


About Visual BC:
I think the only solution is to not change anything here because it seems
very difficult to me. Maybe there could be a similar setting like the
TS_COMPAT switch, I don't know...(?)


About System stability:
Sebastian has written an upgrade wizard which seems to become the perfect
solution for such problems. I see good chances to make this part of 4.0...


- michael
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