pub trait CollectionObj {
type Item;
// Required method
fn boxed_iter(&self) -> Box<dyn Iterator<Item = &Self::Item> + '_>;
}Expand description
A CollectionObj provides the boxed_iter method which returns a boxed iterator over shared references
of elements of the collection.
It is the object safe counterpart of Collection trait which can conveniently be made into a trait object.
Note that for collections, CollectionObj is implicitly implemented and readily available.
Please refer to Collection documentation for details of automatic implementations.
In order to use object safe iterables and collections please add --features std and use
use orx_iterable::{*, obj_safe::*} to import dependencies rather than use orx_iterable::*.
§Examples
use orx_iterable::obj_safe::*;
use arrayvec::ArrayVec;
use smallvec::{smallvec, SmallVec};
use std::collections::{BTreeSet, BinaryHeap, HashSet, LinkedList, VecDeque};
struct Stats {
count: usize,
mean: i64,
std_dev: i64,
}
/// we need multiple iterations over numbers to compute the stats
fn statistics(numbers: &dyn CollectionObj<Item = i64>) -> Stats {
let count = numbers.boxed_iter().count() as i64;
let sum = numbers.boxed_iter().sum::<i64>();
let mean = sum / count;
let sum_sq_errors: i64 = numbers.boxed_iter().map(|x| (x - mean) * (x - mean)).sum();
let std_dev = f64::sqrt(sum_sq_errors as f64 / (count - 1) as f64) as i64;
Stats {
count: count as usize,
mean,
std_dev,
}
}
// example collections that automatically implement Collection
statistics(&[3, 5, 7]);
statistics(&vec![3, 5, 7]);
statistics(&LinkedList::from_iter([3, 5, 7]));
statistics(&VecDeque::from_iter([3, 5, 7]));
statistics(&HashSet::<_>::from_iter([3, 5, 7]));
statistics(&BTreeSet::<_>::from_iter([3, 5, 7]));
statistics(&BinaryHeap::<_>::from_iter([3, 5, 7]));
let x: SmallVec<[_; 128]> = smallvec![3, 5, 7];
statistics(&x);
let mut x = ArrayVec::<_, 16>::new();
x.extend([3, 5, 7]);
statistics(&x);Required Associated Types§
Required Methods§
Sourcefn boxed_iter(&self) -> Box<dyn Iterator<Item = &Self::Item> + '_>
fn boxed_iter(&self) -> Box<dyn Iterator<Item = &Self::Item> + '_>
Creates a new iterator in a box yielding references to the elements of the collection; i.e.,
type of elements is &Item.