Python 2.2 / Properties

[Chris Liechti]

[posted and mailed]

nikolai.kirsebom at siemens.no (Nikolai Kirsebom) wrote in 
news:3c345e9d.108916173 at news.mch.sni.de:

> I have not downloaded the new version yet - but will do so in the new
> future.
> 
> One question relating to the Properties.
> 
> I'm currently developping a small "inspector" where I from a Python
> program will be able to read/write attributes of C++ objects in
> another process (where Python is not possible to integrate).  I'll
> also be able to execute some methods.  Anyhow, system is based on
> useing socket for communication and the protocol is very simple.  Text
> string consisting of object name and attribute name separated by '.'.
> As an example:
> 
> cmd="Object.Attr1"
> will send the command to read Attr1 of the object named "Object".
> 
> cmd="Object.Attr2=345"
> will send the command to set Attr2 to the value 345 of the same
> object.
> 
> (I'm using bison/flex to parse the commands).
> 
> Now to the question:  I would like to use the same property-get and
> property-set methods (functions) for the remote attributes (as seen
> from Python).  The example code below illustrates this.
> 
> --------------------------
> class RemoteObj(object):
>     name = "abc"
>     def remPropGet(self, x):
>         # Send command to remote object to set attribute value
>         resp = Cmd.Send("%s.%s" % (name, NAME_OF_THIS_PROPERTY(x)))
>         if resp['Status'] == OK:
>             return resp['Result']
>         return resp['Default']
>         
>     def remPropSet(self, newVal):
>         resp = Cmd.Send("%s.%s=%s" % (name, NAME_OF_THIS_PROPERTY(x),
> str(newVal)))
> 
>     RecordId = property(remPropGet, None, None, "RecordId")
>     ItemNbr = property(remPropGet, remPropSet, None, "ItemNbr")
> --------------------------
> 
> But is it possible in the methods to find out the name of the property
> being 'handled' - or maybe I somehow could get to the doc-string for
> the property.
> 
> Thanks for any hints/help.

why not use __getattr__ and __setattr__ ?

>>> class A:
... 	def __getattr__(self, item):
... 		try:
... 			return self.__dict__[item]
... 		except:
... 			if item not in ('__members__',): #because of pythonwin
... 				print "get", item
... 				return "hello"
... 	def __setattr__(self, item, value):
... 		if item in self.__dict__:
... 			self.__dict__[item] = value
... 		else:
... 			print "set", item, value
... 
>>> a = A()
>>> a.h
get h
'hello'
>>> a.v = 2
set v 2

the special attributes like __members__ etc are not yet handled correct by 
the above code.

chris

> Nikolai Kirsebom
> 
> 
> 



-- 
Chris <cliechti at gmx.net>