Iterators for collections inside structs

help
1

What is the idiomatic way to expose an iterator for a collection that is embedded inside a struct? For example, I have a struct which has a bunch of helper functions to make it easier to access the data inside the actual collection.

I have an all func to return the underlying vector, so that the caller can do an iter() on it.

struct MyCollection {
    data: Vec<i32>,
}

impl MyCollection{
    pub fn get_by_some_calc1(&self, index: i32) -> i32 { ... }
    pub fn get_by_some_calc2(&self, index: i32) -> i32 { ... }
    pub fn all(&self) -> Vec<&i32> { self.data.iter().collect() }
    ...
}

for idx in my_collection.all().iter() {
    ...
}

Is there a better option to return an iterator, without returning the underlying data, or implementing a new iterator for each type?

2 
pub fn all(&self) -> impl Iterator<Item=&i32> { self.data.iter() }

-> impl Trait means this function returns some concrete type without indirection or dynamic dispatch, but the caller doesn't know anything about this concrete type except it implements this trait.

3

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