[Python-Dev] New syntax for 'dynamic' attribute access

[Johann C. Rocholl]

> On 2/13/07, Nick Coghlan <ncoghlan at gmail.com> wrote:
> [snip]
> > I've tried this out on Brett's urllib & urllib2 examples below. (calling
> > the new builtin attrview() to emphasise the fact that it retains a
> > reference to the original instance). I don't consider it any uglier than
> > the proposed syntax changes, and it provides a few other benefits:
> >
> >    - the two-argument form is naturally available as the .get() method
> > on the resulting dict-like object (e.g. "attrview(obj).get(some_attr,
> > None)")
> >
> >    - hasattr() is naturally replaced by containment testing (e.g.
> > "some_attr in attrview(obj)")
> >
> >    - keywords/builtins are easier to look up in the documentation than
> > symbolic syntax
> >
> > With this approach, performance would be attained by arranging to create
> > the view objects once, and then performing multiple dynamic attribute
> > accesses using those view objects.

On 2/13/07, Collin Winter <collinw at gmail.com> wrote:
> This changes my vote: +1 on including attrview(), -1 on the syntax proposal.

Me too!

I imagine that the addition of the proposed "obj.[name]" syntax to
Python 2.6 would lead to more software that will not run on 2.5 and
earlier versions. I don't think the benefits outweigh this backward
incompatibility of new code. Therefore I'm -1 on including
"obj.[name]" in Python 2.6. For Python 3000, I think it would be
alright.

With "attrview(obj)[name]" it would be possible to provide a fallback
implementation in the same module for pre-2.6 users, so +1 for that.

Johann C. Rocholl