On Sunday, 16 February 2020 at 12:38:51 UTC, Jonathan M Davis
wrote:
On Sunday, February 16, 2020 3:41:31 AM MST uranuz via
Digitalmars-d-learn wrote:
I have reread presentation:
http://dconf.org/2015/talks/davis.pdf
We declare that `pure` input range cannot be `unpoped` and we
can't return to the previous position of it later at the time.
So
logically there is no sence of copying input range at all. So
every Phobos algorithm that declares that it's is working with
InputRange must be tested for working with range with disabled
A range that can't be copied is basically useless. Not only do
almost all range-based algorithms take their argumenst by value
(and thus copy them), but foreach copies any range that it's
given, meaning that if a range isn't copyable, you can't even
use it with foreach. And since many range-based algorithms
function by wrapping one range with another, the ability to
copy ranges is fundamental to most range-based code.
This is working fine with disabled postblit...
import std;
struct SS
{
@disable this(this); // Disabled copy
bool _empty = false;
bool empty() @property {
return _empty;
}
void popFront() {
_empty = true;
}
int front() @property { return 10; }
}
void main()
{
foreach( it; SS() ) { writeln(it); }
}
Am I missing something?
