<story><title>Release of IPython 5.0</title><url>http://blog.jupyter.org/2016/07/08/ipython-5-0-released/</url></story><parent_chain><item><author>jdimov10</author><text>This is fine as far as wishful thinking goes, but simply doesn&amp;#x27;t correspond to reality. Over the past 15 years or so I have been working with and consulting large corporations using Python, all over the world. And I can tell you for a fact: Python 3 is simply not an option in most cases. I HAVE worked on transitioning several large codebases from 2 to 3 and in each case this has been months of work, incurring completely unjustified costs. The benefits have been practically negligible. I would never advise a client with an existing codebase to move on to Python 3, unless there were damn good reasons for it.&lt;p&gt;For new, smaller projects, that don&amp;#x27;t have too many external dependencies - Python 3 is fine. Again, even in these cases, the benefits are largely superficial.</text></item><item><author>Cyph0n</author><text>Found the Python 2 developer folks!&lt;p&gt;Joking aside, Python 3 is the &lt;i&gt;only&lt;/i&gt; Python. The only people who should use Python 2 are those supporting legacy codebases, and even they should start migrating.</text></item><item><author>jdimov10</author><text>Python 2 isn&amp;#x27;t going anywhere anytime soon. Tools and libraries which drop support for Python 2 will suffer and will either revert their decision or be replaced with something else.</text></item><item><author>quantumtremor</author><text>Glad to hear improvements to the shell ipython interface, especially up&amp;#x2F;down arrows on pasted code.&lt;p&gt;The most interesting part of this for me is that IPython 6 will not support Python 2.&lt;p&gt;&amp;gt;Projects such as Matplotlib and SymPy plan to drop support in the next few years, while a few projects like Scikit-Bio are already ahead of us, and should be Python 3 only soon.&lt;p&gt;This was also very surprising for the standard reasons, especially for a library like matplotlib. Glad to find Python moving forward. But what will companies stuck on Python2 do? Will libraries like numpy, matplotlib, and scipy all maintain a Python2 LTS?</text></item></parent_chain><comment><author>carreau</author><text>Making new release of Open-Source &amp;amp; free library python 3 only does not prevent your clients to still use the old versions. Those will never become incompatible. If the want longer support they then can consider giving some money to the Open-Source project they use. The switching at this point for many of the libraries&amp;#x2F;project that make these decision is almost 0 cost, and number of benefits. Especially when these libraries are maintained by Night and Week-end contributors. I think many contributors to these library would &lt;i&gt;&lt;/i&gt;love&lt;i&gt;&lt;/i&gt; to be hired to work on it, and many of these library would &lt;i&gt;&lt;/i&gt;love&lt;i&gt;8 to get funding to hire their contributor. I&amp;#x27;m actually seating to 2 of these people that were hired by such kind of funds, and are now looking for more funding to hire more dev.&lt;p&gt;Saying new versions will not be Python 2 compatible is not a request for Companies to upgrades. It&amp;#x27;s just a statement that they will be stuck on old version of libraries, unless they &lt;/i&gt;&lt;i&gt;buy&lt;/i&gt;* support for a vendor.&lt;p&gt;We (the IPython team) have no objection if Continuum or Enthought provide a Paying version of IPython 6.x that is Python 2 compatible, but that&amp;#x27;s their problem. It does not prevent either the core developer of the Python-3 only project to consult on potential Python 2 internal fork.&lt;p&gt;I honestly think that this would be a much sane model that would make both sides of the Py2vsPy3 battle happy.</text></comment>
<story><title>Release of IPython 5.0</title><url>http://blog.jupyter.org/2016/07/08/ipython-5-0-released/</url></story><parent_chain><item><author>jdimov10</author><text>This is fine as far as wishful thinking goes, but simply doesn&amp;#x27;t correspond to reality. Over the past 15 years or so I have been working with and consulting large corporations using Python, all over the world. And I can tell you for a fact: Python 3 is simply not an option in most cases. I HAVE worked on transitioning several large codebases from 2 to 3 and in each case this has been months of work, incurring completely unjustified costs. The benefits have been practically negligible. I would never advise a client with an existing codebase to move on to Python 3, unless there were damn good reasons for it.&lt;p&gt;For new, smaller projects, that don&amp;#x27;t have too many external dependencies - Python 3 is fine. Again, even in these cases, the benefits are largely superficial.</text></item><item><author>Cyph0n</author><text>Found the Python 2 developer folks!&lt;p&gt;Joking aside, Python 3 is the &lt;i&gt;only&lt;/i&gt; Python. The only people who should use Python 2 are those supporting legacy codebases, and even they should start migrating.</text></item><item><author>jdimov10</author><text>Python 2 isn&amp;#x27;t going anywhere anytime soon. Tools and libraries which drop support for Python 2 will suffer and will either revert their decision or be replaced with something else.</text></item><item><author>quantumtremor</author><text>Glad to hear improvements to the shell ipython interface, especially up&amp;#x2F;down arrows on pasted code.&lt;p&gt;The most interesting part of this for me is that IPython 6 will not support Python 2.&lt;p&gt;&amp;gt;Projects such as Matplotlib and SymPy plan to drop support in the next few years, while a few projects like Scikit-Bio are already ahead of us, and should be Python 3 only soon.&lt;p&gt;This was also very surprising for the standard reasons, especially for a library like matplotlib. Glad to find Python moving forward. But what will companies stuck on Python2 do? Will libraries like numpy, matplotlib, and scipy all maintain a Python2 LTS?</text></item></parent_chain><comment><author>orf</author><text>&amp;gt;  I HAVE worked on transitioning several large codebases from 2 to 3 and in each case this has been months of work, incurring completely unjustified costs&lt;p&gt;Out of interest whats the biggest time sink while doing this? I&amp;#x27;ve had a lot of luck using 2to3 and with decent test coverage and a UAT environment that people can access, its not exactly months and months of work changing &amp;quot;xrange&amp;quot; to &amp;quot;range&amp;quot;, and &amp;quot;print&amp;quot; to &amp;quot;print()&amp;quot;</text></comment>