On 8/24/21 1:44 PM, Ferhat Kurtulmuş wrote:
> Just out of curiosity, if a range implementation uses malloc in save, is
> it only possible to free the memory with the dtor?
Yes but It depends on the specific case. For example, if the type has a
clear() function that does clean up, then one might call that. I don't
see it as being different from any other resource management.
> Is a save function only meaningful for GC ranges?
save() is to store the iteration state of a range. It should seldom
require memory allocation unless we're dealing with e.g. stdin where we
would have to store input lines just to support save(). It would not be
a good design to hide such potentilly expensive storage of lines behind
save().
To me, save() should mostly be as trivial as returning a copy of the
struct object to preserve the state of the original range. Here is a
trivial generator:
import std.range;
struct Squares {
int current;
enum empty = false;
int front() const {
return current * current;
}
void popFront() {
++current;
}
auto save() {
return this;
}
}
void main() {
auto r = Squares(0);
r.popFront(); // Drop 0 * 0
r.popFront(); // Drop 1 * 1
auto copy = r.save;
copy.popFront(); // Drop 2 * 2 only from the copy
assert(r.front == 2 * 2); // Saved original still has 2 * 2
}
Ali
