Immutability

Fredrik Lundh fredrik at pythonware.com
Wed Jun 28 19:28:06 CEST 2006


Nick Maclaren wrote:

> I wasn't expecting EITHER to be turned INTO a property - I was expecting
> both methods to be the same, but one would have non-default properties
> attached to it.

> |> that's what the documentation
> |> says, and that's what your code is doing.
> 
> Er, no, it doesn't.  What it says may well be COMPATIBLE with that, but
> it is compatible with a good many other interpretations, too.  Until and
> unless you know what it means, you can't extract its meaning from its
> words.

well, I completely fail to see how the following is compatible with the 
interpretation "attaches a non-default property, but doesn't do anything 
else":

   property([fget[, fset[, fdel[, doc]]]]) => descriptor

   Returns a property attribute for new-style classes (classes that
   derive from object).

   fget is a function for getting an attribute value, likewise fset is a
   function for setting, and fdel a function for deleting, an
   attribute. Typical use is to define a managed attribute x:

   class C(object):
       def __init__(self): self.__x = None
       def getx(self): return self.__x
       def setx(self, value): self.__x = value
       def delx(self): del self.__x
       x = property(getx, setx, delx, "I'm the 'x' property.")

</F>




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