Can I reference 1 instance of an object by more names ? rephrase

[Bruno Desthuilliers]

Maric Michaud a écrit :
> Stef Mientki a écrit :
(snip)
>> # I need to read and write the individual bits of the byte object
>> # so I can create 8 blocks of code like this, one for each bit position
>> # I use it, like this
>> #    name1 = cpu_ports()
>> #    name1.p5 = True
>> # or
>> #    name1.p[5] = True
>>
>>      @apply   # read / write bit 5
>>        def p5():
>>          def fset(self, value):
>>              index    = 5
>>              value    = ( value & 1L ) << index
>>              mask     = ( 1L ) << index
>>              self._d  = ( self._d & ~mask ) | value
>>          def fget(self):
>>              index    = 5
>>              return ( self._d >> index ) & 1
>>          return property(**locals())
>>
>> I can optimize the above code a little bit,
>> but I've the feeling that I don't need to repeat this code 8 times.
> 
> something like that should just work (untested) :
> 
> def bit():
>     def fset(self, value):
>         index    = 5
>         value    = ( value & 1L ) << index
>         mask     = ( 1L ) << index
>         self._d  = ( self._d & ~mask ) | value
>     def fget(self):
>         index    = 5
>         return ( self._d >> index ) & 1
>     return property(**locals())
> 
> 
> class cpu_ports(object) :
> 
>     p1 = bit()
>     p2 = bit()
>     p3 = bit()
>     p4 = bit()
>     p5 = bit()


As a side note, properties are just an example of objects using the 
descriptor protocol. You can build your own descriptors for more 
advanced use (think : 'smart' attributes):

http://users.rcn.com/python/download/Descriptor.htm
http://docs.python.org/ref/descriptors.html