Speed up properties?!

[Andrew Bennetts]

On Fri, May 14, 2004 at 07:48:29AM +0200, Dr. Peer Griebel wrote:
> Hi,
> 
> I have a class with some properties.  I would like to verify that only
> valid values are assigned to the properties using assert.  Therefore I
> code setters and getters and use property() to convert these to have a
> real property.
> 
> Since the verification is only performed in __debug__ runs the
> property() is quite a lot of overhead.  I tried to circumvent it.  This
> is my result so far:
> 
> 
> class C(object):
>     def __init__(self):
>         self._x = 5
>         if not __debug__:
>             self.x = property(self._x, self._x)

This doesn't really do what you want: properties (and descriptors in
general) only work their magic when they are attributes of classes, not
instances.

I think a simpler approach in your __init__ would do what you want:

    def __init__(self):
        if __debug__:
            self.x = 5   # ordinary attribute
        else:
            self._x = 5  # use properties

The rest looked fine to me.

-Andrew.