[Grok-dev] Grok-dev Digest, Vol 70, Issue 7

Paul Sephton prsephton at gmail.com
Tue Jul 17 16:24:35 UTC 2012

Hi, Uli

On 17/07/2012 12:16, Uli Fouquet wrote:
> Hi Paul,
> On Tue, 17 Jul 2012 07:26:44 +0200 Paul Sephton wrote:
>> On 16/07/2012 14:00, grok-dev-request at zope.org wrote:
>>> If installing a virtualenv is still recommended (and from my point of
>>> view it is), we could make it the default (turning ``--virtualenv`` into
>>> ``--no-virtualenv``).
>>> Beside this we might want an additional ``--download-base`` option to
>>> allow download from other locations than PyPI.
>>> What would be the cons/side-effects?
>> I was under the impression that virtualenv was no longer required?
> Under special circumstances, I think, you still want virtualenvs.
> Especially with some distributions that package eggs in a way not
> compatible with setuptools. That can change from release to release (as
> we now have seen with Feodora). As Sylvain said: in 90% of bootstrap
> problems virtualenv seems to help.
That's cool; I think it's a pity that those distros clash with 
setuptools, and it's understandable that creating an independent 
installation is preferable to hacking one's way through the version 
difference problems.  It will always be a problem where some python apps 
insist on newer egg versions than other python apps.

The way system libraries handle the version difference problems is 
interesting by comparison.  By incrementing major library version only 
when the API interface changes, and incrementing the minor version 
whenever anything else changes, and naming the module to include major & 
minor numbers, it is possible to maintain binary compatibility after 
linking and yet allow for incremental library upgrades.  Effectively, 
older libraries may live alongside newer libraries ad-infinitum.  
Python, on the other hand, expects libraries to have potential 
incompatibility only between interpreter versions, and actual library 
names remain the same between updates regardless of incompatible 
changes.  I'm sure there is something one could do, thinking about it.
>> An immediate problem I could think of, is integration of the dev
>> environment with tools like Eclipse (esp. for code
>> completion/debugging).  As it stands, the eggs go in the ~/.buildout
>> directory.  This would be different for virtualenv?  How would one tell
>> Eclipse to share the same virtual environment?  I have never used
>> virtualenv, so it's a bit intimidating :-)
>> Speaking of this, integration with Eclipse/pydev/Aptana  is still not
>> easy, even with the existence of recipes to help out on that front.
>> There are just so many packages to add to the pythonpath.  If I could
>> add an item to the wishlist...
> Of course you can :-) Just out of curiosity (as I never used Eclipse
> with Python myself): what packages/recipes are required?
Eclipse & Python rocks!  You absolutely need to try it to see if it 
suits you.

The Eclipse package to install is pydev (part of Aptana Studio- 
http://www.aptana.com/).  Aptana can be installed as a standalone, or as 
part of Eclipse.  It also includes a remote debugger (pydevd) which is 
hugely useful when developing for Grok.  Somebody put together 
pb.recipes.pydev, which creates a new pydev project that contains all 
the Zope modules in the projects pythonpath.  I don't use that though, 
and instead add the modules I use manually- it's quite workable to do 
that, although it's a bit clumsy.

To add pydev to Eclipse (3.4+), go "Help->Install New Software", then 
type in "http://pydev.org/updates" in the "Work with" box and click 
"Add".  To use the remote debugger, ensure that the directory containing 
the "pydevd.py" is in your pythonpath, and add "import pydevd; 
pydevd.settrace()" to your code at your intended breakpoint.

pydev gives you syntax highlighting/checking, introspection, command 
completion, and a great debugger.  It also fully integrates DJango- 
which might be useful for someone else out there.  I don't use it myself.

Just by the way, what are your thoughts on web2py as opposed to Grok?


We will have solar energy as soon as the utility companies solve one
technical problem -- how to run a sunbeam through a meter.

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