• Per =?UTF-8?B?Tm9yZGzDtnc=?= (16/16) Sep 16 2018 If I have
• Neia Neutuladh (3/7) Sep 16 2018 import std.traits;
• Per =?UTF-8?B?Tm9yZGzDtnc=?= (7/16) Sep 16 2018 Thanks.

Per =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

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.

Neia Neutuladh <neia ikeran.org> writes:

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];

Per =?UTF-8?B?Tm9yZGzDtnc=?= <per.nordlow gmail.com> writes:

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.