[TransWarp] component config info

[Phillip J. Eby]

At 03:50 PM 2/10/03 -0800, Joel Boehland wrote:
>Hello Phillip,
>Thanks for your explanation on loading config info for components. I just 
>got it to work, and I thought I'd send a little code example to the list 
>in case others aren't clear on this.
>
>file conf/component.ini:
>[mycomponent.dottedpath]
>somekey="blah"
>
>
>file componentconfigtest.py:
>
>from peak.api import *
>
>class ConfigComponent(binding.Component):
>     def getKey(self):
>         key = "mycomponent.dottedpath.somekey"
>         return self._getConfigData(key,self)
>
>if __name__ == "__main__":
>     cc = ConfigComponent()
>     config.loadConfigFile(cc, "conf/component.ini")
>     key = cc.getKey()
>     print key #should print "blah"

Although _getConfigData() is part of the IConfigSource interface, it is 
intended for use only via the 'config' API functions, e.g. 
config.getProperty().  A simpler version of your example would be:

class ConfigComponent(binding.Component):
     myKey = binding.bindToProperty('mycomponent.dottedpath.somekey')

if __name__ == "__main__":
     cc = ConfigComponent()
     config.loadConfigFile(cc, "conf/component.ini")
     print cc.myKey


One reason to use the config functions rather than _getConfigData() 
directly is that _getConfigData() *only* looks up data in the immediately 
referenced object; it will not acquire utilities or properties defined 
higher up in the component hierarchy.

Depending on what you're trying to do, you may wish to define a base class 
that automatically loads the configuration file upon __init__(), or perhaps 
that loads it when __instance_implements__ is first 
accessed.  peak.config.config_components has an example of this, 
'BasicConfig', where a 'setup()' method is called upon the first attempt to 
retrieve configuration data.