Nullable instantiator anyone?
"Nordlöw" via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Sun Aug 17 12:05:10 PDT 2014
On Sunday, 17 August 2014 at 18:51:38 UTC, bearophile wrote:
> It could be sufficient, but note that in Phobos there are two
> different versions of Nullable, one of them doesn't require
> extra memory, it uses one value as the "null" value.
Ok, thanks for the reminder.
Do you have a suggestion of an instantiator for this variant? I'm
not sure how to define this. So far I have
Nullable!T nullable(T nullValue, T)(T a, T nullValue)
{
return Nullable!nullValue(a);
}
unittest
{
auto x = nullable!(int.max)(3);
}
but it fails as
mangling.d(50,21): Error: undefined identifier T
How do I make the template parameter nullValue infer type T with
a single template parameter? Is it even possible?
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