On Thu, 07 Oct 2010 11:42:06 +0400, Brad Roberts <bra...@puremagic.com>
wrote:
On 10/6/2010 11:58 PM, Walter Bright wrote:
Russel Winder wrote:
Python may be the best base to compare things to as tuple assignment
has
been in there for years.
Pythons choice is not a car/cdr approach but an exact match approach.
so if t represents a tuple datum or a function returning a tuple:
x = t
then x is a tuple -- remembering that variables are all just references
to objects implemented via keys in a dictionary, and:
a , b , c = t
or
( a , b , c ) = t
is tuple assignment where now t is required to be a tuple of length 3.
cf.
The first thought was to make it an exact match approach. Andrei
thought that
the car/cdr one was better, though, and I find it intuitively
appealing, too.
Perhaps Python missed an important use case?
Or perhaps the ambiguity as to whether the last item gets to be a value
or
another tuple is too much.
I think the ambiguity should be avoided. There was one language I used
ages ago
that used a token to signal the use of the last arg as a 'rest' usage.
If I
remember right, it used:
(a, @b) = aggregate; // a = aggregate[0], b = aggregate[1..$]
It also allowed: (a, @aggregate) = aggregate; // essentially a pop
operation.
That said, it was a weakly typed language, so it's application to D has
to be
taken with an appropriate dose of salt. For D, I think using the @
would clash
badly with the attribute syntax, so an alternative that's not horrid:
(a, b...) = aggregate;
Later,
Brad
Interesting idea, I like it!
