On 03/29/2013 05:39 PM, kenji hara wrote:
2013/3/30 bearophile <bearophileh...@lycos.com
<mailto:bearophileh...@lycos.com>>
kenji hara:
I think it will become reasonable. If you really want re-packing
tuple, you
can use {tup[0..1]}. It's quite handy.
This is a bad idea. It is not handy and it introduces a special
case. Explicit is better than implicit.
That is "explicit". In D, opened tuple (currently it's generated from
template parameters, e.g. std.typetuple.TypeTuple) and closed tuple
(currently created by structs with alias tuple_field this; e.g.
std.typecons.Tuple) are distinct. Slice operator always returns opened
tuple.
Because of prior language limitations, not because it makes any sense!
Current operator overloading limitations mandate that it is simply not
possible to create a Phobos tuple with a sane slice operator.
If tup[0..1] makes closed tuple implicitly, you cannot make new
flattened tuple from other tuples.
auto x = {1,"hi"};
auto y = {[1,2], S(1)};
auto tup1 = {x[], y[]}; // creates {1,"hi", [1,2], S(1)}
auto tup2 = {x, y}; // creates {{1,"hi"}, {[1,2], S(1)}}
Under your semantics, it is impossible.
...
Certainly not. Creating opened tuples from closed ones is not an
operation necessarily tied to slicing.
Making an opened tuple should be an explicit operation on closed tuples.
Slicing and opening are orthogonal operations.
auto tup1 = {x.open, y.open}; // creates {1,"hi", [1,2], S(1)}
auto tup2 = {x[0..2], y[]}; // creates {{1,"hi}, {[1,2], S(1)}}
auto tup3 = {x[0..2].open, y[].open}; // creates {1,"hi", [1,2], S(1)}
