Most power users mays already know this. But this is a real enlightenment for newbies who are stuck with the command line pdb utility. Even for experienced developper as I am... supposed to be, this is a real advantage to have on screen at the same time the source code, with breakpoints in the margin of it, the inspector for your global and local variables, the access to the call stack and execution frames.
Start reading the fine manual here and come back reading how to get this in Zope 2.
Of course I assume you have a recent Eclipse (Indigo) and Pydev (2.2.4)
Find in your Eclipse software directory the full path of the directory that contains pydevd.py. In other words :
$ cd /your/eclipse/root $ find . -name 'pydevd.py'
In my MacBook the file is found in /Developer/eclipse/plugins/org.python.pydev.debug\_184.108.40.2061110216/pysrc
(note that upgrades of PyDev may change this path to something else)
Edit your development buildout config file and add this in your plone.recipe.zope2instance part:
[instance] recipe = plone.recipe.zope2instance # ... extra-paths = /Developer/eclipse/plugins/org.python.pydev.debug_220.127.116.111110216/pysrc
Of course re-run your buildout. Open the debug perspective in Eclipse and start the PyDev debugger server (see link above).
You can now add anywhere you want (need) the line:
or create and useuse the shortcut "pydevd" to insert your first hard breakpoint.
Start your Zope instance and make the necessary clicks to execute the line that has the hard breakpoint. Wow, great : the next line of Python to be executed is hilited from there, you cand step, step over, go to the next return, and even add soft breakpoint double clicking in the left margin anywhere in your source code.
All other things you may need to know about debugging with PyDev are here and usable "as is" in a Zope server.
Another great feature for those who develop with Windows: when debugging with Eclipse/Pydev you can start your development instance as a service, when before you needed to run the sloooooow "instance fg" and benefit of Eclipse remote debugging.