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```operator fun Body.iterator(): Iterator<Body> { val body = this return object : Iter...
# getting-started
j
Copy code
operator fun Body.iterator(): Iterator<Body> {
    val body = this
    return object : Iterator<Body> {
        var current: Body? = body

        override fun hasNext(): Boolean {
            return current != null
        }

        override fun next(): Body {
            val result = current!!
            current = result.getNext()
            return result
        }
    }
}
c
s/b 
this@iterator
or similar to get you back to the enclosing method.
m
The 
next
function is throwing the wrong exception based on the contract from Java. Kotlin has no contract on what to do if 
next
cannot return anything.
j
Yeah I would suggest adapting to a 
Sequence
instead, so you don't have to deal with the iterator interface yourself
Something like this:
Copy code
fun Body.asSequence(): Sequence<Body> = sequence {
    var current: Body? = this@asSequence
    while(current != null) {
        yield(current)
        current = current.getNext()
    }
}
https://pl.kotl.in/Uk-KSmcQL
j
@Joffrey thanks. the reason I like iterator is that a for loop knows how to apply the iterator operator automatically. with the sequence approach I'd have to call .asSequence explicitly right?
j
That's right. It's a fair point. You could of course implement the 
iterator()
operator with 
asSequence().iterator()
but you may as well just implement it directly like you just did.
✅ 1
s
There's also an 
iterator { ... }
builder that works exactly like the 
sequence { ... }
builder.
😯 1
j
TIL
s
It's funny that it's not more well-known! Especially since the implementation of 
sequence { ... }
is just 
= Sequence { iterator(block) }
.
It never seems to be mentioned in the docs. Maybe iterators just aren't cool these days 😄.
j
To be fair I rarely use 
for
loops, so I rarely implement the 
iterator
operator. And mutating a list while iterating is something I haven't had to use in Kotlin at all (for years), and this was the main reason to use iterators directly
So I get the "iterators are not cool anymore" part :)
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