Andrei Alexandrescu, el 7 de octubre a las 03:20 me escribiste:
> On 10/7/10 1:43 CDT, Russel Winder wrote:
> >On Wed, 2010-10-06 at 23:08 -0700, Walter Bright wrote:
> >>If expr represents a tuple, we (Andrei and I) were thinking about the
> >>syntax:
> >>
> >> auto (a, b, c, d) = expr;
> >>
> >>being equivalent to:
> >>
> >> auto t = expr; auto a = t[0]; auto b = t[1]; auto c = t[2 .. $];
I guess d being missing is a typo, right?
> >>You can also do this with arrays, such that:
> >>
> >> float[3] xyz;
> >> auto (x, y, z) = xyz;
> >>
> >>The Lithpers among you will notice that this essentially provides a handy
> >>car,cdr shortcut for tuples and arrays:
> >>
> >> auto (car, cdr) = expr;
> >
> >
> >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 then we'd have the proposed notation not work with dynamic arrays
> - only with static arrays and tuples.
Unless you add a dynamic "bound" check as when accessing a dynamic array
item, something like:
auto t = expr; assert (t.lenght == 4); auto a = t[0]; auto b = t[1];
auto c = t[2]; auto d = t[3];
I like the idea of having exact match approach and the explicit syntax
for getting the rest as Brad said. But in all the years I used Python,
I never needed that syntax, maybe because most of the times when I use
the tuple expansion I know the size or I want to truncate, or I use
something to generate the data, like split(), that takes an extra
parameter to do that:
l = [1, 2, 3]
a, b, c = l # known lenght
a, b = l[:2] # truncation (like l[0..2] in D)
a, b = '1,2,3'.split(',', 1) # get the rest in b (but it will be a string)
car, cdr = l[0], l[1:] # just a little more verbose
--
Leandro Lucarella (AKA luca) http://llucax.com.ar/
----------------------------------------------------------------------
GPG Key: 5F5A8D05 (F8CD F9A7 BF00 5431 4145 104C 949E BFB6 5F5A 8D05)
----------------------------------------------------------------------
careful to all animals (never washing spiders down the plughole),
keep in contact with old friends (enjoy a drink now and then),
will frequently check credit at (moral) bank (hole in the wall),
