computed multiple assignment

[John W. Eaton]

On 30-Jan-2010, Jaroslav Hajek wrote:

| I've discovered that using the computed assignment operators works in
| [a, b] += deal (1, 2)
| 
| but not
| [a{1:2}] += deal (1, 2).
| 
| It would take some effort to make the latter work, but I doubt the
| capability is useful at all, and apparently it is not being used
| anywhere (it seems it isn't even documented). I vote for removing it -
| see the attached patch. Anyone objects?

I have no objection to this change.  If we agree that

  X op= Y

is always supposed to be shorthand for

  X = X op Y

then unless we able to use comma-separated lists in expressions, I
don't see how it makes any sense for the LHS of the op= operator to
take multiple arguments.

jwe