[Python-Dev] Features for Python 2.0

Thomas Wouters thomas@xs4all.net
Tue, 25 Jul 2000 15:20:44 +0200

On Tue, Jul 25, 2000 at 04:00:07PM +0300, Moshe Zadka wrote:

> OK, here's a possible confusion point in augmented assignments:

> Sometimes

> c = a
> a += b
> assert  a is c

> fails, and sometimes not, depending on a's type. This is just begging
> for trouble. Maybe it will cause massive confusion, maybe it won't. I know
> I'll usually be wary of using it.

In my very honest opinion, that's overstating it a bit. It isn't much more
confusing than the failure of

  c = a + b
  assert c is a + b

for some types, but not for others. Not to mention that

  a + b

can produce an entirely different object than

  b + a

depending on the types. Now, how's that for confusing ! Has anyone ever seen
a problem caused by that ? I haven't, and I doubt the augmented assignment
is going to cause such problems. I *have* seen something like this:

  c = a.extend(b)

Though that was a real silly mistake on the programmers part, and hasn't
repeated itself.

All in all, the only way we are really going to spot these pitfalls,
realistic or not, is by *using* the new syntax, and letting 'newbies' use

Thomas Wouters <thomas@xs4all.net>

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