rust-ndarray / ndarray

The type IntoIter implemented in #986 is not exposed publicly, which makes it difficult or impossible to implement IntoIterator trait for custom types wrapping ndarray:

use ndarray::iterators::IntoIter; // Module `iterators` is private

pub struct Foo {
  array: Array1<i32>,
}

impl IntoIterator for Foo {
  type Item = i32;
  type IntoIter = IntoIter<i32, Ix1>; // `IntoIter` is private
  fn into_iter(self) -> Self::IntoIter {
    self.array.into_iter()
  }
}

The type is private in it's own module, re-exported publicly from module iterators, however module iterators itself is not public in lib.rs:

ndarray/src/lib.rs

Line 191 in 97ecc0d

mod iterators;

The sibling types Iter and IterMut are exposed additionally in lib.rs

ndarray/src/lib.rs

Line 146 in 97ecc0d

use crate::iterators::{ElementsBase, ElementsBaseMut, Iter, IterMut};

I believe that the reason why the author of the PR missed this is the unnecessary spaghetti of re-exports. There seem to be no particular pattern in place. Why is this complexity needed? How it can be improved?

Proposed changes:

expose IntoIter publicly to solve this problem directly
refactor public exports to avoid unnecessary complexity and prevent this kind of bugs from happening again
add tests validating public interface of the library; require these tests to be added along with the new functionality in PRs affecting public interface

It should be in https://docs.rs/ndarray/latest/ndarray/iter/index.html and if it is not, it is a bug

I don't think it's impossible - <Array1<i32> as IntoIterator>::IntoIter should be available to you?

Type `IntoIter` is private