Hi,

Namespace helped me to get following template working.

struct PrimitiveRef(T)
{
	private T* _value;

	@property
	ref inout(T) get() inout pure nothrow {
		assert(_value);
		return *_value;
	}
	
	alias get this;
	
	this(T val) {
		_value = new T(val);
	}
}

The use case is a type tuple where you cannot use the keyword ref.

Example usage: ( This is an extract from a little event framework)

Event!(Object, BoolRef) onClose;

onClose.attach(&onFormClose); // function or delegate

void onFormClose(Object o, BoolRef canClose)
{
    canClose = false;
}

I think it is useful to add to std.typecons as there is no possibility
to use ref for type tuples.

Kind regards
André

Definition of BoolRef:

alias BoolRef = PrimitiveRef!bool;

On Tuesday, 24 March 2015 at 15:38:04 UTC, Andre wrote:
> The use case is a type tuple where you cannot use the keyword ref.

Could template alias parameters not be used here?

http://dlang.org/template.html#aliasparameters

On Tuesday, 24 March 2015 at 16:58:48 UTC, Gary Willoughby wrote:
> On Tuesday, 24 March 2015 at 15:38:04 UTC, Andre wrote:
>> The use case is a type tuple where you cannot use the keyword ref.
>
> Could template alias parameters not be used here?
>
> http://dlang.org/template.html#aliasparameters

Event is defined as struct Event(T...){}.
That way the actual number of parameters is very flexible.

I just checked template alias parameters. Also here the ref keyword
is not allowed:

	struct Event(alias x)
	{
		private void delegate(x)[] _dlgArr;
	}

	Event!(ref bool) onEvent;

Error is thrown: expression expected not ref.

Kind regards
André

On Tuesday, 24 March 2015 at 15:38:04 UTC, Andre wrote:
> I think it is useful to add to std.typecons as there is no possibility
> to use ref for type tuples.

This sounds like a bad idea because in D `ref` is not a type qualifier and thus not part of a type. Not though that you can apply ref storage class to type tuple as a whole:

void foo(T...)(ref T args) { }