Crate anon_iter 

anon_iter is a much lighter alternative to the auto_enums crate, being less general-purpose but solving the most common use-case of this pattern (impl Iterator), without relying on macros - leading to much faster compile times and simpler syntax.

It does this by providing generic wrapper types like AnonIter2 to allow to return different types of iterators from a function that returns -> impl Iterator.

Usage

Add this to your Cargo.toml:

[dependencies]
anon_iter = "0.1"

Wrap each iterator in AnonIter2 to return 2 different iterators from the same function:

use anon_iter::AnonIter2;

fn foo(x: i32) -> impl Iterator<Item = i32> {
    match x {
        0 => AnonIter2::I1(1..10),
        _ => AnonIter2::I2(vec![5, 10].into_iter()),
    }
}

The crate Either allows similar functionality, as it too implements Iterator when its type parameters are both Iterator.

But this breaks down when you want to return 3 or more Iterators because you now have to do extra nesting (e.g. Either::Left(Either::Right(Either::Left(my_iter)))). With anon_iter, it’s just AnonIter8::I3(my_iter).

Additionally, anon_iter makes code more readable because it may not be instantly obvious that we are using Either for this purpose, but with AnonEnum the intent is apparent.

Enums

AnonIter2

Wraps 2 impl Iterators which may be of different types

AnonIter3

Wraps 3 impl Iterators which may be of different types

AnonIter4

Wraps 4 impl Iterators which may be of different types

AnonIter5

Wraps 5 impl Iterators which may be of different types

AnonIter6

Wraps 6 impl Iterators which may be of different types

AnonIter7

Wraps 7 impl Iterators which may be of different types

AnonIter8

Wraps 8 impl Iterators which may be of different types

AnonIter9

Wraps 9 impl Iterators which may be of different types

AnonIter10

Wraps 10 impl Iterators which may be of different types

AnonIter11

Wraps 11 impl Iterators which may be of different types

AnonIter12

Wraps 12 impl Iterators which may be of different types