[TransWarp] component path - property name dualism, does this make sense?

Phillip J. Eby pje at telecommunity.com
Mon Aug 18 15:48:51 EDT 2003

At 08:35 PM 8/18/03 +0200, Matthias Drochner wrote:

>pje at telecommunity.com said:
> > Have you looked at  ZConfig?
>Thanks for your reply -- while I consider the XML-like syntax not
>too well suited for end-"users", it has its advantages, and since
>in my case the config-file-supplied data are primarily for
>testing in absence of the real database, this is acceptable.
>I'll look into it; this might take a while...

I'll also note that there is another possibility here...  it may be that 
PEAK components are the wrong tool for the job you're trying to do.  If 
these axes and suchlike components are really dynamic, and want to come 
from a database, it may be that the peak.model package offers better tools 
for the job (and can handle persistence and transactions via 
peak.storage).  But that depends a bit on what your overall schema looks like.

Alas, peak.model is even less well documented at present than peak.binding 
and peak.config.  But feel free to post your questions and I will do my 
best to answer them.

Also, here's a slightly cleaned up alternative to your original post:

class ConfigDelegate(binding.Component):

     def propertyMap(self,d,a):
         path = binding.getComponentPath(self)
         return PropertyName('devconfig.' + '.'.join(path[1:-1])).of(self)

     propertyMap = binding.Once(propertyMap)

     def __getattr__(self, attr):
         value = self.propertyMap.get(attr,NOT_FOUND)
         if value is NOT_FOUND:
             raise AttributeError(attr)
         return value

class testaxis(binding.Component):

         instancesProvide = [movable.Imovable]

     currentpos = 0
     moving     = 0
     logger     = binding.bindToProperty('logging.movement')
     delegate   = binding.New(ConfigDelegate)

     speed = ll = ul = binding.delegateTo('delegate')

     def __init(self, d, a):
         self.logger.debug('testaxis: initializing %s', self.path)

     __init = binding.whenAssembled(__init)

Now, as you can see, you need only have a ConfigDelegate in your classes, 
and use delegateTo to lookup the data.  I left your '__init()' method in 
place above, mainly to illustrate that it's not necessary to use a lambda: 
to call it, and also to illustrate that you really don't need the method at 

This approach uses a slightly different config structure, here's your 
example .ini file recast for the above:


* = naming.LinkRef('tacodb:movetest.%s/' % ruleSuffix)

group1.member1.ll = 0
group1.member1.ul = 100
group1.member1.speed = 0.4
group1.member2.ll = 0
group1.member2.ul = 100
group1.member2.speed = 0.2

Now, any data that is not supplied in the configuration file, will come 
from your 'tacodb' thing.  I presume that that's what your use case for 
this is, anyway.  That is, you want to have data come from the DB unless 
you override it in the config file.

More information about the PEAK mailing list