dynamism

[Steven Shaw]

"Duncan Booth" <duncan at NOSPAMrcp.co.uk> wrote in message
news:Xns92855D48384F9duncanrcpcouk at 127.0.0.1...
> steven_shaw at adc.com (Steven Shaw) wrote in
> news:66715c02.0209091923.265fe77e at posting.google.com:
>
> >
> > I thought you could just extend an object's attributes at run-time
> > like this:
> >
> >>>> p = object()
> >>>> p.x = 1
> > Traceback (most recent call last):
> >   File "<stdin>", line 1, in ?
> > AttributeError: 'object' object has no attribute 'x'
>
> New style classes (which are those with 'object' or other builtin classes
> as a base class) do not all allow you to add arbitrary attributes:
>
> If you have an object which is a builtin type (object, int, dict, ...)
then
> you cannot add attributes. If you have an object which is a subclass of a
> builtin type, then you can add attributes unless the subclass defined a
> member __slots__.
>
> The __slots__ attribute in a class, if defined, lists all of the attribute
> names settable in instances of that class. If no __slots__ attribute is
> directly defined in a class then you may add arbitrary attributes (this
> applies even if __slots__ is set in a base class).
>
> An object of a builtin type, or with __slots__ defined in the class and
> all base classes does not have a __dict__ attribute.

Does this mean that the attributes are stored in a more efficient way?

Is there a way to implement "record-based" object layout rather than
"associative-array based" object layout?


Cheers, Steve.