{"id":435,"date":"2010-11-05T21:51:59","date_gmt":"2010-11-06T02:51:59","guid":{"rendered":"http:\/\/www.insomnihack.com\/?p=435"},"modified":"2011-06-01T22:06:56","modified_gmt":"2011-06-02T03:06:56","slug":"python-3-with-virtualenv-and-macports","status":"publish","type":"post","link":"https:\/\/www.insomnihack.com\/?p=435","title":{"rendered":"Python 3 with Virtualenv and Macports"},"content":{"rendered":"

Update<\/strong>: As of virtualenv 1.6, Python 3 is supported out of the box, so all this is no longer necessary. I touch on it briefly in this post<\/a>.<\/p><\/blockquote>\n

In my last post<\/a>, I described how to get all the various versions of Python currently supported by Macports<\/a> working together on OSX with virtualenv<\/a> and virtualenvwrapper<\/a>. There was one small problem, though. If you tried to create a new virtual environment with Python 3, you’d encounter this error:<\/p>\n

[text]
\n$ mkvirtualenv –no-site-packages –python=\/opt\/local\/bin\/python3.1 bar
\nRunning virtualenv with interpreter \/opt\/local\/bin\/python3.1
\nFile "\/Library\/Python\/2.6\/site-packages\/virtualenv-1.5.1-py2.6.egg\/virtualenv.py", line 17
\nexcept ImportError, e:
\n ^
\nSyntaxError: invalid syntax
\n[\/text]<\/p>\n

This occurs because the except<\/em> syntax has changed<\/a> in Python 3, and setuptools<\/a>, pip<\/a>, and virtualenv haven’t been updated as yet. However, we can still get Python 3 to play nice with virtualenvwrapper. With Brandon Rhode’s virtualenv3<\/a> fork and a bit of bash profile arcanum, we can get Python 3 to play nice with virtualenvwrapper and the other versions of Python installed on our system.<\/p>\n

First, go grab virtualenv3 from bitbucket<\/a> and install it using Python 3. The example below assumes you’ve installed Python 3.1 and python_select<\/a> via macports as described in my last post, and that the default Snow Leopard Python 2.6.1 is active.<\/p>\n

[text]
\nsudo python_select python31
\nhg clone http:\/\/bitbucket.org\/brandon\/virtualenv3
\ncd virtualenv
\npython setup.py develop
\nsudo python_select python26-apple
\n[\/text]<\/p>\n

Now open your bash ~\/.profile in an editor and add the following aliases and functions:<\/p>\n

[text]
\nalias mkve24=’mkvirtualenv –no-site-packages –python=\/opt\/local\/bin\/python2.4′
\nalias mkve25=’mkvirtualenv –no-site-packages –python=\/opt\/local\/bin\/python2.5′
\nalias mkve26=’mkvirtualenv –no-site-packages –python=\/opt\/local\/bin\/python2.6′
\nalias mkve27=’mkvirtualenv –no-site-packages –python=\/opt\/local\/bin\/python2.7′
\nfunction mkve31() {
\n \/opt\/local\/bin\/python3.1 \/Users\/daledavis\/Source\/virtualenv3\/virtualenv3.py –no-site-packages $WORKON_HOME\/$@
\n}
\n[\/text]<\/p>\n

This assumes you have virtualenvwrapper installed with the WORKON_HOME environment variable. Also note that the mkve31 function body is all on one line despite what my skinny WordPress theme might suggest.<\/p>\n

Now we should be able to create virtual environments with all the installed Python versions without hang up. Open up a new terminal and try creating a Python 2.7 and Python 3.1 virtual environment. If all is as it should be, you should see something very similar to what I’ve pasted below.<\/p>\n

[text]
\n$ mkve27 py27
\nRunning virtualenv with interpreter \/opt\/local\/bin\/python2.7
\nNew python executable in py27\/bin\/python
\nInstalling setuptools……………………….done.
\nvirtualenvwrapper.user_scripts Creating \/Users\/daledavis\/VirtualEnvs\/py27\/bin\/predeactivate
\nvirtualenvwrapper.user_scripts Creating \/Users\/daledavis\/VirtualEnvs\/py27\/bin\/postdeactivate
\nvirtualenvwrapper.user_scripts Creating \/Users\/daledavis\/VirtualEnvs\/py27\/bin\/preactivate
\nvirtualenvwrapper.user_scripts Creating \/Users\/daledavis\/VirtualEnvs\/py27\/bin\/postactivate
\nvirtualenvwrapper.user_scripts Creating \/Users\/daledavis\/VirtualEnvs\/py27\/bin\/get_env_details
\n(py27)$ mkve31 py31
\nNew python executable in \/Users\/daledavis\/VirtualEnvs\/py31\/bin\/python
\nInstalling setuptools…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………done.
\n(py27)$ python –version
\nPython 2.7
\n(py27)$ workon py31
\n(py31)$ python –version
\nPython 3.1.2
\n[\/text]<\/p>\n","protected":false},"excerpt":{"rendered":"

Update: As of virtualenv 1.6, Python 3 is supported out of the box, so all this is no longer necessary. I touch on it briefly in this post. In my last post, I described how to get all the various versions of Python currently supported by Macports working together on OSX with virtualenv and virtualenvwrapper. […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[30],"tags":[9,6,8],"_links":{"self":[{"href":"https:\/\/www.insomnihack.com\/index.php?rest_route=\/wp\/v2\/posts\/435"}],"collection":[{"href":"https:\/\/www.insomnihack.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.insomnihack.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.insomnihack.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.insomnihack.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=435"}],"version-history":[{"count":0,"href":"https:\/\/www.insomnihack.com\/index.php?rest_route=\/wp\/v2\/posts\/435\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.insomnihack.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=435"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.insomnihack.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=435"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.insomnihack.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=435"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}