On Sat, Jun 26, 2010 at 10:06 AM, Christian Heimes <li...@cheimes.de> wrote:

> Am 26.06.2010 17:59, schrieb Stefan Reich:
> > The main problem is that Python 3 is incompatible with almost all
> > scripts written for Python 2 (if they use print). And it gets worse:
> > Python 3 scripts are incompatible with Python 2! (If they use print
> > variants, like writing to a file.)
>
> Seems like you don't know that you can easily migrate your scripts with
> the tool "2to3". Also you can write Python 3 compatible scripts in
> Python 2.6 and newer: from __future__ import print_function.
>
> Christian
>
>
This comment and many others in this thread fail to address the substance of
the OP's point. Languages such as Python and Perl have adopted the strange
practice of making new versions of the language backwards incompatible. Many
other languages such as Java remain backwards compatible and thus do not
alienate their userbase.

I would also like to point out in this thread a bit of evidence that this
was a bad idea: Python 3 adoption has been extremely slow and it is still
not a sure bet that it will ever become very popular. I am not alone in
having tens of thousands of lines of python 2 code, and you can bet that all
of us have edge cases that the 2to3 tool is not going to catch. That means
that in order to run old code in Python 3 we have to first run the tool and
then sanity check it to make sure it has the same behavior (and honestly, do
you really have test cases for every bit of Python you've ever written? No,
and neither do the rest of us.). Where the tool fails we have to find out
why and then go fix our code.

Nobody wants to be involved in this hassle. At best you can hope in the
future that both Python 2 and 3 will be installed on user's systems, and
Python 2 will be the default executable. But expect it to be a very, very
long time before Python 3 adoption overtakes Python 2. There is simply no
impetus to do it. The "upgrades" to the language are lost on 99% of the
users who first bought into Python because they already liked it and they
have no interest in learning a new version. Myself included.
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