[mod_python] mod_python.Importer.path; set dynamically

Martijn Moeling martijn at xs4us.nu
Tue Feb 12 04:43:48 EST 2008


Thank you, I did not mess around with it yet, I am planning a  
versioning system to be added to my webbased development platform.
I am still having some trouble with my webdav module, I have to taccle  
that one first.

Your help is usefull one question though:

say the inporterpath is set to:


in the apacheconfig the importerpath is set to .../python_modules

in both directories stays:

modulex.py ( in the me directory is the lates version)

in my handler module:

import modulex

de handler(req):
	....... (some code)
	if req.debug and req.session.loggedIn:
		req.options['mod_python.path'] = ".../me:../"
           for module in modules:
			module.append( apache.import_module(module)
		return module.index(req,*args,**kwargs) # return apache.OK?
   ......... (some code)
	return apache.OK

what happens to the interpreter for the next requests? which "modulex"  
is used ? The are supposed to get the "stable" one from .../ 
I don't understand what the return line does, what happens if I return  
apache.OK in this case?


On Feb 5, 2008, at 11:12 AM, Graham Dumpleton wrote:

> Sorry for the delay.
> To make things work transparently across a lot of modules, for both
> import_module() and 'import' where possible, what you can do is modify
> the value of option 'mod_python.importer.path' dynamically from code.
> This can be done from memory using:
> req.options['mod_python.importer.path'] = "...."
> You obviously can query this first if you need to somehow manipulate
> it to add stuff.
> All you then need is a level of indirection. Has to be from inside of
> handler, can't be at global scope. So,
> /var/www/python_modules/index.py might do:
> def index(req, *args, **kwargs):
> req.options['mod_python.importer.path'] = \
>  '/var/www/python_modules/%s:/var/www/python_modules' % req.user
> module = apache.import_module('index-core')
> return module.index(req, *args, **kwargs)
> If there is only one level of module imports, you could also do just:
> def index(req, *args, **kwargs):
> module = apache.import_module('index-core', \
>  path=['/var/www/python_modules/%s:/var/www/python_modules' %  
> req.user]))
> return module.index(req, *args, **kwargs)
> but think that if subdirectory uses 'import', then it might not look
> in all the directories. Can't remember how it works now.
> Anyway the suggestion is look at changing req.options if you haven't  
> already.
> Graham
> On 01/02/2008, Martijn Moeling <martijn at xs4us.nu> wrote:
>> Graham,
>> As you might remember I added a MySQLdb section to session.
>> (to be able to save sessions across computers)
>> In my system a lot of additional data is added to the req object,  
>> which is
>> passed
>> around. in my case it is req.Session.user.
>> (I do not use http based auth, since this is in conflict with my  
>> web based
>> desktop)
>> nevertheless, i can change your "example code" to my needs, consider
>> req.user as the distinguisher for ease of thinking.
>> Martijn
>> -----Original Message-----
>> From: Graham Dumpleton [mailto:graham.dumpleton at gmail.com]
>> Sent: Thu 31.01.2008 23:03
>> To: Martijn Moeling
>> Cc: mod_python at modpython.org
>> Subject: Re: [mod_python] mod_python.Importer.path; set dynamically
>> On 01/02/2008, Martijn Moeling <martijn at xs4us.nu> wrote:
>>> Hi!
>>> I am an extensive mod_python user and my system needs something  
>>> special.
>>> Consider the following:
>>> in httpd.conf I have :
>>> PythonOption mod_python.importer.path ["/var/www/python_modules"]
>>> /var/www/html/index.py is linked to ../python_modules/index.py
>>> the python_modules directory has subdirectories, like; developer1,
>>> developer2
>>> the python_modules contains stable modules and developerX holds
>> development
>>> versions.
>>> I have load balancing with multiple frond-ends (apache/MP) and one
>> backend
>>> (MySQL).
>>> I would like to dynamically change the mod_python.importer.path so  
>>> that
>>> developer1 runs code in the corresponding subdir if the module  
>>> exists,
>>> else fall back to the python_modules directory.
>>> Any tips, suggestions, remarks?
>> What is the distinguisher used to know which developer it is? Are you
>> using something like Basic authentication and so could distinguish
>> based on req.user?
>> If you tell me what the distinguisher is, probably have an idea.
>> Graham

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