On Wed, 01 Jun 2011 16:38:42 -0400, KennyTM~ <[email protected]> wrote:
On Jun 2, 11 04:05, Steven Schveighoffer wrote:
On Wed, 01 Jun 2011 15:38:32 -0400, Andrej Mitrovic
<[email protected]> wrote:
It seems to do even more than that:
int a;
const int b;
immutable int c;
shared int d;
shared(const int) e;
static assert(is(typeof(cast()a) == int));
static assert(is(typeof(cast()b) == int));
static assert(is(typeof(cast()c) == int));
static assert(is(typeof(cast()d) == int));
static assert(is(typeof(cast()e) == int));
Talk about stealing the storm from std.traits.Unqual..
On 6/1/11, KennyTM~ <[email protected]> wrote:
While checking the Phobos source I've found an interesting expression
cast()(result[i]) = to!(E)(e);
The 'cast()' means 'cast to mutable', e.g.
class S {}
void g(S x) {}
void main() {
const S s;
g(cast()s);
}
But this is not documented in the D spec (CastParam cannot be empty).
Is
this an "accept-invalid" bug, or just a feature not yet documented?
It gets even better:
char[] x = "abc".dup;
assert(is(typeof(cast(const)x) == const(char[]));
I think you may have found a "bug" that should be a feature. It's like
dmd is organically growing features that we might need ;) Is this
software evolution? Scary!
When will dmd decide that human life is a disease to be eradicated? When
will the world be dominated by constinators?!!! I fear for my children.
All kidding aside, I actually think the syntax makes sense. You are
adding/removing modifiers, so just leave the type out of it. The only
drawback is, you can't do a cast directly to a tail-const array, but
that's not a huge deal, since const(T[]) implicitly casts to const(T)[].
I dub this feature "Type Modifier Casting".
-Steve
cast(const), cast(immutable) etc are documented. cast() is not. See
http://d-programming-language.org/expression.html#CastExpression
:O
Of course, by documented, it shows the cast in the grammar (BTW, why the
separate rule for cast(Type) when CastParam can be Type?), but not in the
text. I almost never read the grammar unless I'm confused by the docs.
This is almost as good as const_cast, although it seems too easy to screw
up and remove const when you don't want to.
-Steve
