The path to BFG: virtualenv bfgenv and _socket PYTHONHOME PYTHONPATH activate

The BFG python web framework folks pride themselves on their testing - but I can't say the same for virtualenv when installed under Windows.  And in this regard, the BFG web documentation is lacking (compared, say, to WebCore.)

First, the point of virtualenv is to be able to maintain a BFG server on a machine with python26 and python27 and python31  as we transition to python32 and beyond.  So they move a copy of some version of python.exe and pythonw.exe into a Scripts folder.  But they neglect to supply the respective python DLL. So copy that from your PYTHONHOME into that new bfgenv/Scripts directory.

The scripts will not work correctly if you do not first clean up your cmd environment by executing the following at that DOS shell prompt:

set PYTHONPATH=

but even then I have found that for my sanity I need to go into the new /bfgenv/Scripts and edit the activate.bat and deactivate.bat files to preserve and restore my %PYTHONPATH% as well %PYTHONHOME%

One symptom that there is a problem is having an install script complain about not finding a module which imports without problem in your 'normal' python environment.  In my case it was _socket

Sadly, I read advice on mail lists to reinstall Python.  "There must be something wrong with your Python install" as you will see by a web search on virtualenv _socket

Here is a set of steps which will work on Windows XP for Python 2.7 if \python27\Scripts is on your PATH

cd \python27

python ez_setup.py            (note: get this python script off the web for SetupTools)

easy_install virtualenv

set PYTHONPATH=

cd \

virtualenv --no-site-packages bfgenv

cd \bfgenv

Scripts\activate

Scripts\easy_install -i http://dist.repoze.org/bfg/current/simple repoze.bfg

cd Scripts

python test_bfg_port_28686.py   (note: this last is your test file - remember to choose a port)

Suppose PYTHONHOME had been conceived as a string such as

"27*c:\python27;31*i:\python312"

then this would not be an issue - so long as PYTHONPATH was not built by subst of %PYTHONHOME% or $PYTHONHOME

But that ship has sailed.

And take care when in \bfgenv to issue the command as

Scripts\activate.bat

because, like me, you may have more than one activate.bat in your path ... I mean, %PATH%.

Here is a 2009 blog post on using virtualenv: Chris Scott

The WebCore pages suggest using pip. And what could be simpler than

pip install CherryPy

PS
Of course, BFG on linux installed and ran like a charm ...
PPS
Check that %PYTHONHOME%\Scripts is on your PATH