How to check if value is null, today?

jfondren julian.fondren at gmail.com
Thu Oct 14 12:43:36 UTC 2021


On Thursday, 14 October 2021 at 11:58:29 UTC, tastyminerals wrote:
> Here is an example code that doesn't work with the new compiler 
> anymore:
>
> ```
> if (someValue.isNull)
> ```
>
> Attempting to run the above throws:
> ```
> Error: incompatible types for `(0) : (someValue)`: `int` and 
> `Nullable!int`
> ```
>

Do you have a complete example? Because this runs without error:

```d
import std.typecons : nullable, Nullable;
import std.stdio : writeln;

void main() {
     auto a = nullable(1);
     auto b = Nullable!int.init;
     if (!a.isNull)
         writeln(a.get);
     if (b.isNull)
         writeln("b is null");
}
```


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