On Tuesday, 3 June 2025 at 16:03:15 UTC, Andy Valencia wrote:
I have a situation where chain()'ing them together would be
convenient, but InputRange requires front() and popFront().
As an exercise in chaining opApply based containers, I tried:
```d
// Chain across containers; their type is T and what they hold is
type B
class Chain(T,B) {
private T[] members;
this(T...)(T args) {
foreach(m; args) {
this.members ~= *m;
}
}
int
opApply(int delegate(ref B) ops) const {
int res = 0;
foreach(m; this.members) {
foreach(val; m) {
res = ops(val);
if (res) {
break;
}
}
}
return res;
}
}
```
I'm a little iffy on the walk of the args and the *m deref. But
it tests out OK in practice. Using one looks like:
```d
import tiny.set : Set;
alias SetInt = Set!int;
auto s1 = new SetInt();
s1.add(1);
s1.add(2);
s1.add(3);
auto s2 = new SetInt();
s2.add(4);
s2.add(5);
s2.add(6);
auto s3 = new SetInt();
foreach(x; new Chain!(SetInt,int)(s1, s2)) {
s3.add(x);
}
```
Andy
