On Wednesday, 11 February 2026 at 12:41:50 UTC, Brother Bill
wrote:
On Tuesday, 10 February 2026 at 20:37:04 UTC, Nick Treleaven
wrote:
If you add a copy constructor to Duration, you can see when it
gets copied:
```
this(ref Duration d)
{
this.tupleof = d.tupleof;
writeln("copying Duration: ", toString);
}
```
The ```ref``` is needed to avoid yet another copy.
It's more that `ref` is part of what signifies a copy constructor:
https://dlang.org/spec/struct.html#struct-copy-constructor
Please explain what ```this.tupleof = d.tupleof;``` does in
detail.
It copies the fields of `d` to the fields of `this`.
https://dlang.org/spec/class.html#tupleof
