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Python Source Code Beautifier

sjdevnull at yahoo.com sjdevnull at yahoo.com
Wed Feb 28 17:09:09 EST 2007 
On Feb 28, 11:24 am, Alan Franzoni
<alan.franzoni_inva... at geemail.invalid> wrote:
> Il 27 Feb 2007 16:14:20 -0800, sjdevn... at yahoo.com ha scritto:
>
>
>
> > Those mean different things:
>
> >>>> a=[1]
> >>>> b=a
> >>>> a += [2]
> >>>> a
> > [1, 2]
> >>>> b
> > [1, 2]
> >>>> a=[1]
> >>>> b=a
> >>>> a = a + [2]
> >>>> a
> > [1, 2]
> >>>> b
> > [1]
>
> This is a really nasty one! I just answered to Tim above here, and then I
> saw your example... I had never realized that kind of list behaviour.
> That's probably because i never use + and += on lists (i prefer the more
> explicit append() or extend() and i do copy list explictly when I want to)
> , BTW I think this behaviour is tricky!

Seems obvious and desirable to me.  Bare "=" is the way you assign a
name to an object; saying "NAME =" will rebind the name, breaking the
connection between a and b.  Without it, they continue to refer to the
same object; extending the list (via += or .extend) mutates the
object, but doesn't change which objects a and b are referencing.

It would be very counterintuitive to me if "=" didn't change the
name's binding, or if other operators did.
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