> I just > couldn't get through on the python-dev list that I couldn't just > upgrade my code to 2.6 and then use 2to3 to keep in step across the > 2-3 chasm, as this would leave behind my faithful pre-2.6 users.
Not sure whom you had been talking to. But I would have tried to explain that you don't *have* to port to 2.6 to use 2to3 - it will work just as fine with 2.3 code, and earlier. > - No use of sets. Instead I defined a very simple set simulation > using dict keys, which could be interchanged with set for later > versions. This I don't understand. IIUC, you want to support 2.3 and later. Now, 2.3 already has a set module, even though set is not a builtin. So you could use sets just as well. > - No generator expressions, only list comprehensions. Ok. Not sure how this causes problems, though - just don't use them, then. > - No use of decorators. BUT, pyparsing includes a decorator method, > traceParseAction, which can be used by users with later Pythons as > @traceParseAction in their own code. Of course, users of older Python versions could explicitly wrap the functions with the decorator if they wanted to. > - No print statements. As pyparsing is intended to be an internal > module, it does no I/O as part of its function - it only processes a > given string, and returns a data structure. If you don't need them, fine. If you do, I'd just let 2to3 transform them. > - Python 2-3 compatible exception syntax. This may have been my > trickiest step. The change of syntax for except from > > except ExceptionType, ex: > > to: > > except ExceptionType as ex: > > is completely forward and backward incompatible. The workaround is to > rewrite as: > > except ExceptionType: > ex = sys.exc_info()[0] Likewise, and more importantly so: use 2to3. It can be done this way, but I find the 2to3 solution much cleaner. > But in > the meantime, I am still able to support all versions of Python NOW, > and I plan to continue doing so (albeit "support" for 2.x versions > will eventually mean "continue to offer a frozen feature set, with > minimal bug-fixing if any"). The same would have been possible if you had chosen to use 2to3. Regards, Martin -- http://mail.python.org/mailman/listinfo/python-list
