Should Stream.iteratorStream be deprecated?

[clinuxrulz]

The following static method in Stream is unsafe.

public static <A> Stream<A> iteratorStream(final Iterator<A> it)

Due to Stream's use of WeakRef, when you visit the elements of Stream you can get a different result on the 2nd pass. (Internal mutable iterator keeps its state while cache is cleared)

I think this method should be avoided at all times because its behavior is unpredictable.

[jbgi]

👍
I am also wondering if the Stream<->java.util.Stream should be subject to the same deprecation (in the java8 module). Will have a look.

[clinuxrulz]

Splitterators created with the correct Characteristics should be safe (unsure). Maybe Stream<->java.util.Stream can be made safe, rather than deprecated.

[clinuxrulz]

https://docs.oracle.com/javase/8/docs/api/java/util/stream/package-summary.html

Down the bottom.

"Consumable. The elements of a stream are only visited once during the life of a stream. Like an Iterator, a new stream must be generated to revisit the same elements of the source."

Java 8 Streams are designed for 1 pass only. So a 2nd pass is a misuse.

[jbgi]

The deprecation of iteratorStream also mean the deprecation of iterableStream which also mean deprecating/refactoring api/implementation of big chunks of IterableW, F1Functions and ParModule.
So... kind of a can of worms :(

[clinuxrulz]

I see. It does not need attention yet. Its just something noticed a year ago that caught me out. Thought I make sure its noticed.

Even a warning in the javadoc that iteratorStream, can be used for constructing single pass Streams ONLY. And throw an Exception if a 2nd pass is detected when constructed with that method?

By throwing an Exception, at least we provide Deterministic behavior.

[clinuxrulz]

IterableW avoids this problems as its usage of streams created by iteratorStream are all single pass.

So safety by documentation? Make people aware of limitations of iteratorStream.