[Web-SIG] Web Site Process Bus

[Ian Bicking]

Phillip J. Eby wrote:
> At 02:28 PM 6/25/2007 -0500, Ian Bicking wrote:
>> Potentially a Zope-style minimal event framework would work.  Maybe 
>> something like:
>>
>>   send_signal(signal_name, signal_data)
>>   subscribe(signal_name, listener)
> 
> That was what I was wondering, too, except I was thinking it would be 
> sufficient to use entry points for subscription, but only invoke the 
> entry points whose modules are in sys.modules.  In other words, never 
> actually import a module in order to invoke a callback.  That way, 
> subscription is a natural side effect of importing the modules that 
> contain the listeners.  Something like:
> 
> def send_signal(group, name, *args, **kw):
>     for ep in iter_entry_points(group, name):
>         if ep.module_name in sys.modules:
>             ep.load()(*args, **kw)

I don't think that makes sense for this case.  The way I imagine using 
it is:

class MyApplication(object):

     def __init__(self, db):
         self.db = db
         subscribe('reload_resources', self.reload)
     def reload(self, data=None):
         self.db.close()
         self.db.open()

That is, I subscribe one particular thing when it is applicable, not 
because the library is on the system.


-- 
Ian Bicking | ianb at colorstudy.com | http://blog.ianbicking.org
             | Write code, do good | http://topp.openplans.org/careers