On 28-Jul-12 13:00, Stuart wrote:
On Saturday, 28 July 2012 at 08:53:43 UTC, Dmitry Olshansky wrote:
On 28-Jul-12 11:49, Stuart wrote:
But as I understand it, for ranges I'd need to write a whole new class.
struct. Yeah, you need it.
Here, I'm writing a SINGLE FUNCTION in standard imperative style.
That implicitly constructs Iterator.
It's just a sugar. In fact you can do template mixin to generate most
of range boilerplate.
I think the basic thrust of my point is: Sugar is good. The compiler
converting an imperative function into a state-machine class is helpful.
Having to write it yourself every damn time is a pain in the arse.
It would be good to redo opApply so that it does something like this. In
fact look at opApply it's approach is the other way around - instead of
generating object it packs function as delegate and passes it to some
internal iteration mechanism:
for(v; a){
v++;
}
--->
a.opApply(x => x++);
where a's opApply can do whatever it wants to with this delegate and
elements.
I've been reading about ranges at
[http://ddili.org/ders/d.en/ranges.html], and don't understand
something. Where it says:
struct StudentRange {
Student[] students;
this(School school) {
this.students = school.students;
}
[...code...]
Surely "students" is copied here? Isn't the whole point NOT to copy the
array? Perhaps it should say:
this.students = school.students[];
?
Okay. You also need to learn how D arrays or rather slices work :)
It copies 2 words: pointer and length. Thus students points to the same
array in both cases.
To make a full copy use .dup. You really need to checkout Steven's D
slices article can't recall link offhand.
--
Dmitry Olshansky
