Eclipse with PyDev under OS X Lion


Blog categories: 

Yesterday I wanted to start using the Eclipse extension PyDev, because I was tired of using the pdb module. Even more sophisticated debugging modules like pudb did not satisfy my need for intuitive and comfortable python debugging. Even though I heard of the PyDev extension quite a while ago, I never gave it a try, as I was reluctant using the Eclipse Framework for Python.

As already said, yesterday I took comfort and installed PyDev in my local Eclipse installation using Install New Software... from the Help menu. The installation process was finished in a wink and I could start my application right away using the Run button.

However, when trying to debug (using the bug symbol in the toolbar), I got the following error:

ImportError: dlopen( /System/Library/Frameworks/Python.framework/Versions/2.6/lib/ python2.6/lib-dynload/, 2): Symbol not found: __PyLong_AsScaledDouble

After consulting the all-knowing, all-seeing Trash Heap I found the bug mentioned on StackExchange and thought it might be worth sharing this information with you.

Here is how I fixed the problem: Open the Eclipse-Preferences (⌘-,), advance to PyDev → Interpreter Python and remove the one configuration in the upper list of python interpreters. Then, install python from home brew (or another source of choice) using:

brew install python

and add the brew interpreter to Eclipse PyDev using the location /usr/local/bin/python and a name of your choice. For home brew’s Python you might need to add /usr/local/bin before the occurrence of /usr/bin in your PATH variable as well as /usr/local/share/python.

After the proper installation of an alternative Python and it’s addition to PyDev as the default interpreter, I was able to use PyDev smoothly and get back to work finally.

That’s it!