Re: How to define variadic delegate with a ref/out argument?

[pham via Digitalmars-d-learn]

On Friday, 17 November 2017 at 06:21:50 UTC, Jerry A. wrote:
On Friday, 17 November 2017 at 05:08:23 UTC, pham wrote:
struct DelegateList(Args...)
{
public:
    alias DelegateHandler = void delegate(Args args) nothrow;
    DelegateHandler[] items;

    void opCall(Args args) nothrow
    {
        foreach (i; items)
            i(args);
    }
}

DelegateList!(string, int) list; // Compile OK so far
DelegateList!(string, int*) list2; // Compile OK so far
DelegateList!(string, ref int) list3; // Compile error -> How 
to make it work?

Thanks
Pham

The only way I know of is using  a template which behaves like 
a reference.
Which can be done with nullableRef I suppose. Haven't actually 
tried it.

import std.typecons : NullableRef, nullableRef;

DelegateList!(NullableRef!int)(nullableRef(some_int));

nullableRef is same as passing pointer. Using "ref" is stronger 
guarantee that the var is never be passed as null.

variadic parameter passed by "ref" should be supported

Thanks.
Pham