If I have

    alias N = Nullable!(T, T nullValue)

fed as template parameter to another template how can I

at compile-time get the `nullValue`

?

I need this to implement fast linear search over a slice of type

    Nullable!(ulong, ulong.max)[]

searching for a non-null key without needing to call a combination of Nullable's `isNull` and `get` inside the loop. Which is significantly slower than knowing the non-null value to search for.  Which also can be implemented using sentinel-based search.

In my case it would have been convenient to have public access to

    Nullable!(T, T nullValue)._value

I need this in a hash table of mine that uses open addressing that makes use of Nullable to indicate empty slot.

On Sunday, 16 September 2018 at 16:28:20 UTC, Per Nordlöw wrote:
> If I have
>
>     alias N = Nullable!(T, T nullValue)
>
> fed as template parameter to another template how can I
> at compile-time get the `nullValue` ?

import std.traits;
enum nullValue = TemplateArgsOf!(N)[1];

On Sunday, 16 September 2018 at 16:50:32 UTC, Neia Neutuladh wrote:
> On Sunday, 16 September 2018 at 16:28:20 UTC, Per Nordlöw wrote:
>> If I have
>>
>>     alias N = Nullable!(T, T nullValue)
>>
>> fed as template parameter to another template how can I
>> at compile-time get the `nullValue` ?
>
> import std.traits;
> enum nullValue = TemplateArgsOf!(N)[1];

Thanks.

However, I just realized that I need to cast the array of nullables to an array of underlying unnulled types and search that array using an unnulled key. So I have no use for the nullValue, anyway.