[Python-ideas] aliasing

[Greg Ewing]

Steven D'Aprano wrote:
> Peio Borthelle wrote:
> 
>>>>> a = 2
>>>>> b = alias("a")
>>>>> a = 'foo'
>>>>> b
>>
>> 'foo'
>
> I have often thought that would be a nice to have feature,

Seems to me it would be a confusing-to-have feature. By now
it's deeply embedded in Python programmers' brains that
assignment to a bare name can only change which object that
name refers to, and can't have any other side effects.

> You can always use one level of indirection:
> 
> a = [2]
> b = a
> a[0] = 'foo'  # Not a='foo'
> b[0]
> => print 'foo'

Also, if you're willing to use an object attribute rather
than a bare name, you can get the same effect using a
property.

class Switcheroo(object):

     def get_b(self):
         return self.a

     def set_b(self, value):
         self.a = value

     b = property(get_b, set_b)

s = Switcheroo()
s.a = 17
print s.a
s.b = 42
print s.a

-- 
Greg