Casting by assigning to the right ...

[Mathias LANG]

On Tuesday, 14 April 2020 at 05:56:39 UTC, Manfred Nowak wrote:
> ... is already builtin via properties.
>
> After declaring
> ```
> struct S{ int data;}
> S s;
> int i;
> ```
>
> one often would like to implicitly cast the value of the 
> structure by typing
> ```
> i= s;
> ```

There's two easy ways to accomplish this:
```
struct S
{
     int data_;

     version (OpAssign) ref S opAssign (int v) { this.data_ = v; 
return this; }
     version (AliasThis)
     {
         @property ref int data (int v) { this.data_ = v; return 
this.data_; }
         alias data this;
     }
}

void main ()
{
     S s;
     int i;
     s = i;
}
```

Which one you pick depends on your design. I would recommend the 
`OpAssign` version by default.