On 04/15/2015 03:42 PM, "Nordlöw" wrote:
> On Wednesday, 15 April 2015 at 20:12:27 UTC, Ali Çehreli wrote:
>> Ali
>
> I cracked it:
>
> Reason: I hade a failing unittest using it as
>
> auto xs = x.indexedBy!"I";
>
> which I changed to
>
> auto xs = x.indexedBy!"Ix";
>
> For some reason the mixin magic becomes confused when I equals "I".
>
> Do you have any clues as to why?
That is because you have a nested struct named I inside IndexedBy. :) I
print it with pragma(msg) below. So, mixin(I) is not happy because it
thinks you mean 'struct I' :)
struct IndexedBy(R, string I = "Index") if (isArray!R)
{
enum toMixin = q{ struct } ~ I ~
q{ {
alias T = size_t;
this(T ix) { this._ix = ix; }
T opCast(U : T)() const { return _ix; }
private T _ix = 0;
}
};
pragma(msg, toMixin);
mixin(toMixin);
mixin genOps!(mixin(I));
R _r;
alias _r this; // TODO Use opDispatch instead; to override only
opSlice and opIndex
}
void main()
{
auto i = IndexedBy!(int[], "I")();
}
The output:
struct I {
alias T = size_t;
this(T ix) { this._ix = ix; }
T opCast(U : T)() const { return _ix; }
private T _ix = 0;
}
> Should we restrict IndexedBy to not allow I to equal "I"?
I don't think there is a general solution but you can always disallow as
a template constraint or as a static assert:
struct IndexedBy(R, string I = "Index")
if (isArray!R &&
I != "I") // <-- ADDED
{
// ...
}
>
> :)
>
> Thx anyway.
Ali
