Andrej Mitrovic:
> module test;
>
> struct MyArray(T)
> {
> private T[] data;
>
> bool opCast(T)() if (is(T == bool))
> {
> return !data.empty;
> }
> }
>
> void main()
> {
> auto foo = MyArray!(int)();
> auto state = foo ? true : false;
> }
>
> test.d(13): Error: undefined identifier module test.empty
> test.d(20): Error: template instance test.MyArray!(int).MyArray.opCast!(bool)
> error instantiating
>
> This is straight from the book. Did .empty exist for arrays before? Perhaps
> this was just a typo in the book, and it was supposed to be:
You need this at the top:
import std.array;
> Also, that error message *really* needs to improve. It's not module 'test'
> which is missing the method, it's 'data'. This is one of the most confusing
> error messages that I know of and it pops up all the time.
emopty is not an array method, it's a free function that is used with a funny
syntax.
Bye,
bearophile
