Possible constant assignment operators ":=" and "::=" for Python

[Bruno Desthuilliers]

tsaar2003 at yahoo.com a écrit :
> Yes, I know that "constant" A will also be modified as the b[0] points
> to A. Obviously the [] should be marked as immutable, as A is declared
> to be constant thus immutable. If somebody tries to modify this
> immutable object an error would occur.
> 
> When I further thought about this problem with constant objects (and
> values), I run into this scenario: What if I want to use a constant
> object/value as a template (or predefined value/class) for a variable:
> 
> constant A = ['1'] # let's declare A as immutable constant value/object
> b = A # let's assign b some default value
> b.append('2') # and let's play with b, but I wouldn't want to change A

def A():
   return ['1']

b = A()
b.append('2')