Fixing Python virtualenv on OS X

This weekend I’ve been toying with an old project I created in Django a while (~2 years) ago. The project uses virtualenv, as commonly happens in this kind of projects. The original project was created originally on a different machine, and migrated to the current one. Original machine had OS X Lion, I think… or Snow Leopard, not sure. The point is, the project had been migrated thought 4 or 5 major OS X versions… and Python was a different version from the original one used to create the original virtualenv.

So, back to the problem, trying to use Anaconda for Sublime Text, I found that the Python interpreter I was specifying in the configuration was not working. After some Googling, I found a link (I’m not able to find it again…) on how to troubleshot the configuration, which at the end it boiled down to execute the Python interpreter inside your virtualenv with the following command:

~/Virtualenvs/myvirtualenv/bin/python -c pass

In my case, the result was the folling:

dyld: Library not loaded: @executable_path/../.Python
  Referenced from: ~/Virtualenvs/myvirtualenv/bin/python
  Reason: image not found
[1]    74178 trace trap  ~/Virtualenvs/myvirtualenv/bin/python -c pass

After some Googling about this problem, I found the following post: “dyld: Library not loaded: @executable_path/../.Python” Basically: “dump the packages configuration, recreate the virtualenv, restore packages, and move everything there”. In my case, the “move everything there” was a bit tricky, and the “restore packages” was even worst, as it was using some unsupported packages which was impossible to install (no pip support, and manually install was quite time consuming…). So, I tried to do something in between, and finally I found the real difference, and the reason the interpreter was failing (notice different python version):

$ ls -la old-virtualenv
lrwxr-xr-x   1 myuser  staff      78 29 nov  2014 .Python -> /usr/local/Cellar/python/2.7.5/Frameworks/Python.framework/Versions/2.7/Python

$ ls -la new-virtualenv
lrwxr-xr-x   1 myuser  staff      80  5 mai 22:42 .Python -> /usr/local/Cellar/python/2.7.8_2/Frameworks/Python.framework/Versions/2.7/Python

So, the real fix in my case was:

$ cd old-virtualenv
$ rm .Python
$ ln -s /usr/local/Cellar/python/2.7.8_2/Frameworks/Python.framework/Versions/2.7/Python .Python

Re-enabling Xcode plugins

After updating my Xcode, I noticed that plugins got disabled. To reenable them, the easiest way is just “touching” all the plugin directories:

$ cd ~/Library/Application\ Support/Developer/Shared/Xcode/Plug-ins
$ touch *

After that, restart Xcode and you will get a dialog asking if plugins should be loaded.

An alternate take on this is can be found here: Re-enable Alcatraz on Xcode 6.3.2 or Newer

Additional tip: if the update was the OS, maybe this StackOverflow answer can be also useful: CocoaPods doesn’t work after upgrading Mac OS X EI Capitain.

UPDATE: I’ve updated to Xcode 7.2 today, and suddenly all the plugins stopped to work. There is an update for Alcatraz. See also this tweet.

UPDATE2: There is a new upgrade for Alcatraz for Xcode 7.3. See this tweet. You need to first update it, then “touch” the plugins (see above), execute:

$ defaults delete DVTPlugInManagerNonApplePlugIns-xcodebuild-7.3
$ defaults delete DVTPlugInManagerNonApplePlugIns-Xcode-7.3

Additionally, I guess that some plugins need an update, because they are not working (for example CocoaPods).

Easily manage windows in OS X

I’ve been using OS X for many years already, and as my primary computer OS for almost a year. Before that, I used to spend time with Windows (like 90% of it), Linux (for server) and OS X.

There are two things that I missed after switching from Windows (last version I regularly used was 8.1) to OS X (I started to regularly use it on Tiger), being a heavy keyboard user: the way window cycling works on Windows, and Windows snap (available since Windows 7, including shortcuts).

Window switch

Window switch shortcut on Windows (Alt+Tab) cycles through all your windows, in usage order, but on OS X (Cmd+Tab) cycles through applications. There is a second shortcut, which usually is assigned to Cmd+`. This shortcut is quite cumbersome, at least on Spanish keyboard layout (maybe also on English layout too): as soon you enter in a text field of any kind, if you press this shortcut you get the ` character, waiting for you to complete an accented letter (yes, in Catalan and Spanish languages we have such a thing). Additionally you cycle through your windows immediately, without preview, and without remembering your usage order.

There are two solutions here:

  • change the shortcut in System Preferences (preview and usage order still missing here),
  • use Witch (thanks to Jaume Sánchez for pointing me this out).

I prefer using Witch, as it has lots of options, allowing you to use a switcher more like Windows one, making no distinction between windows and apps, or use it the way I do, which is to use it as an improvement to OS X default way of switching between windows inside an application. BTW I use Alt+Cmd+Tab as this shortcut, and doesn’t conflict with any other shortcut, working all the time.

Windows Snap

When working with many windows, sometimes is useful to be able to “snap” windows to one side of the screen or the other. This feature is really useful on Windows (starting from 7), but I’ve been missing it on OS X since the beginning. Also, maximizing not always maximizes in both directions, but only in vertical (depends on the application). Finally, on OS X “El Capitan”, maximize button has changed to fullscreen as the default option, having to press Alt to maximize. This version of OS X also includes a feature like Snap, but only works for fullscreen apps.

So, recently I found a way of overcoming this and having nice shortcuts “a-la-Windows”: Spectacle. This nice app sits in your menu bar and helps you to quickly resize your windows (snap, fullscreen, even quarter of screen snap), move them between screens, even undo and redo this actions!