On Saturday, June 03, 2017 05:52:55 vit via Digitalmars-d-learn wrote:
> Hello,
> What's the difference between x = Nullable!Test.init and
> x.nullify?
>
>
> class Test{}
>
> void test()pure nothrow{
> Nullable!Test x;
>
> x = Nullable!Test.init; //OK
> x.nullify; //Error: function
> 'std.typecons.Nullable!(Test).Nullable.nullify!().nullify' is not
> nothrow
>
> }
Assigning Nullable!Test.init is equivalent to setting the internal value to
Test.init and setting _isNull to false. nullify doesn't assign
Nullable!Test.init to the Nullable!Test, and it doesn't assign Test.init to
_value. Rather, it calls destroy on _value and sets _isNull to true. Exactly
what destroy does depends on the type. In the case of a class, it calls
rt_finalize on it, which basically calls the class' finalizer (if it has
one). But rt_finalize is not nothrow, so destroy isn't nothrow, so nullify
isn't nothrow. However, looking at what rt_finalize does, I don't see why it
couldn't be nothrow. So, unless I'm missing something, it seems like that
would be a good enhancement.
- Jonathan M Davis
