Dynamic use of property() fails

[Bruno Desthuilliers]

Hrvoje Niksic a écrit :
> Bruno Desthuilliers <bruno.42.desthuilliers at websiteburo.invalid>
> writes:
> 
>>> However, if you know what you're doing, you can simply customize your
>>> class's __getattribute__ to do what *you* want for your objects.
>> <op>
>> But bear in mind that, beside possible unwanted side-effectn, you'll
>> get a non-negligible performance hit - __getattribute__ being, as the
>> name implies, invoked on each and every attribute lookup.
> 
> That's unavoidable, though -- whatever you do to customize your class
> in Python, the result will be slower than the C code built into
> Python.

This one customization hook is probably the most sensible still.

>  Fortunately, not every object is performance-critical.  In
> this case, __getattribute__ buys you per-instance customization not
> otherwise available.  The code you posted is probably more efficient,
> but at the cost of losing the ability to customize specific instances
> of the class.

You could as well just customize __setattr__/__getattr__ (which is what 
was done before new-style classes and descriptors). But my own 
experience is that the very few times I thought I had a need for 
per-instance descriptors, I found other solutions that were certainly 
easier to grasp and maintain on the long term. Not that I would not be 
able to deal with per-instance descriptors, but so far the cost 
outweighted the benefits IMHO. Now YMMV of course !-)