const(Object)ref is here!

[Andrej Mitrovic]

That was fast. 0o

:)

On 12/6/10, Michel Fortin <michel.fortin at michelf.com> wrote:
> After a recent discussion on this list about tail-const class
> references, it became rather clear that someone interested would have
> to implement the thing if we were to have it. So I did it. See
> enhancement request 5325 for an explanation and a patch.
> <http://d.puremagic.com/issues/show_bug.cgi?id=5325>
>
> Let's hope Walter likes my patch.
>
> In the tail-const thread, I proposed the challenge of making this code
> work when an array of const object is passed as an argument:
>
> 	T[] giveMeASortedArray(alias Predicate, T)(T[] t) {
> 		// creating new array of the same length but with assignable elements
> 		auto copy = new Unqual!(typeof(t[0]))[t.length];
> 		foreach (index, value; t)
> 			copy[index] = value;
> 	
> 		// sorting the copy
> 		sort!(Predicate)(copy);
> 		return copy;
> 	}
>
> Well, with the patch I made it now works!... irrespective of the type
> attribute (const,immutable,shared,inout). The only modification
> required to Phobos is to make to!string() compile when passed a
> const(Object) because somehow 'sort' requires that.
>
> Here is how the function is invoked:
>
> 	void main() {
> 		int*[] a = giveMeASortedArray!("a < b")(new int*[12]);
> 		Object[] b = giveMeASortedArray!("a < b")(new Object[12]);
> 	
> 		const(int*)[] c = giveMeASortedArray!("a < b")(new const(int*)[12]);
> 		const(Object)[] d = giveMeASortedArray!("cast(void*)a <
> cast(void*)b")(new const(Object)[12]);
> 	}
>
> See the strange predicate for the const(Object) version? That's because
> opCmp() in Object doesn't work with const.
>
> Two minor modifications are required in Phobos to make the above
> compile. First, to!string(const(Object)) needs an implementation
> because somehow 'sort' requires it. Also template std.traits.isMutable
> needed an adjustment so that swap()'s template constrains are satisfied.
>
>
> --
> Michel Fortin
> michel.fortin at michelf.com
> http://michelf.com/
>
>