On 17/08/2011 10:26, gc wrote:
On Aug 17, 3:13 am, Chris Angelico<ros...@gmail.com> wrote:
Minor clarification: You don't want to initialize them to the same
value, which you can do already:
a=b=c=d=e=dict()
Right. Call the proposed syntax the "instantiate separately for each
target" operator. (It can be precisely defined as a * on the RHS of a
one-into-many assignment statement--i.e. an assignment statement with
1 object on the RHS and more than 1 on the LHS).
I think that lazy unpacking is the more important issue because we can
replace instantiation with copying:
def copies(obj, count=None):
if count is None:
while True:
yield obj.copy()
else:
for i in range(count):
yield obj.copy()
(Should it yield deep copies, or should there be a separate deep_copies
function?)
It has only one very modest function, which is to unpack
a, b, c, d, e = *dict()
to
a, b, c, d, e = dict(), dict(), dict(), dict(), dict()
This becomes:
a, b, c, d, e = copies(dict(), 5)
With lazy unpacking it would become:
a, b, c, d, e = lazy copies(dict())
(Or whatever the syntax is.)
so that you have n separate objects instead of one. If you want the
same object duplicated five times, you'd best use a=b=c=d=e=dict().
(I'd guess that 90% of the people who try the a=b=c version actually
*want* separate objects and are surprised at what they get--I made
that mistake a few times!--but changing either behavior would be a
very bad idea. This proposed syntax would be the Right Way to get
separate objects.)
Maybe this is more visibly convenient with a complex class, like
x, y, z = *SuperComplexClass(param1, param2, kwparam = "3", ...)
x, y, z = lazy copies(SuperComplexClass(param1, etc, ...))
[snip]
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