Hi everyone,

lets say that required is a setter method:

Nullable!string str(Nullable!string setter) {
    return this._str = setter;
}

The user should be able to:

auto a = new A();
a.str = "abc";

As the setters parameter is defined to be of type Nullable!string, the compiler complains. So the user need to do a.str = nullable("abc");

I guess a solution could be to define the setter as:

Nullable!string str(T)(T setter) {
    return this._str = setter;
}

^stupid question: Is this the correct way to restrict the parameter type to be string or Nullable!string or is there a more precise way to restrict?

BTW: here is a more complete simple example of what i am talking about: https://run.dlang.io/is/zP4vkb

On Sunday, 12 December 2021 at 13:42:08 UTC, Martin B wrote:

Nullable!string str(T : {string, Nullable!string}) (T setter) {
    return this._str = setter;
}

You can use a template constraint:

Nullable!string str(T)(T setter)
    if (is(T == string) || is(T == Nullable!string))
{
    return this._str = setter;
}

On Sunday, 12 December 2021 at 14:11:48 UTC, Paul Backus wrote:

Hi Paul,
yes! thats it, Thanks. I am facepalming me right now because have been on that webpage and missed that point.

On Sunday, 12 December 2021 at 14:26:54 UTC, Martin B wrote:

Happens to everyone at some time 🌅