On Wed, Nov 11, 2020 at 01:05:21AM +0000, SealabJaster via Digitalmars-d-learn
wrote:
> Please see the code at https://run.dlang.io/is/Yjidek
[Quoting code in full here for future reference]
> struct PreValidate
> {
> alias FuncT = bool delegate(string arg);
>
> FuncT func;
>
> this(FuncT func)
> {
> this.func = func;
> }
>
> bool onPreValidate(string arg)
> {
> return this.func(arg);
> }
> }
>
> // OK
> @PreValidate(str => str.length == 3)
> int i;
>
> void main()
> {
> // OK
> auto v = PreValidate(str => str.length == 3);
> }
>
> struct S
> {
> // ERROR?
> @PreValidate(str => str.length == 3)
> int a;
> }
> As I understand the error is caused by trying to provide a delegate
> when there's no context to provide. Not complaining about that.
Is this even a valid error? The UDA works in module scope, where there
*isn't* any local context, yet it's accepted, but here, in a struct,
it's not accepted. I'm not 100% but this looks like a bug.
> However what I am complaining about is about the error message:
> `onlineapp.d(31): Error: delegate onlineapp.S.__lambda2 cannot be
> struct members`
>
> I'm not sure if it's just me, but that error message makes absolutely
> no sense to me. Should that message be improved?
Definitely. Bad/confusing error messages should always be improved.
Please file a bug at:
http://issues.dlang.org/
T
--
Unix was not designed to stop people from doing stupid things, because that
would also stop them from doing clever things. -- Doug Gwyn
