I think Java does not allow to have both overloads, because it would
result in ambiguity?
If you call `s1.merge(s2)` it's unclear which method you want to call.
-Matthias
On 3/28/22 7:20 AM, Nick Telford wrote:
Hi Matthias,
How about instead of changing the signature of the existing method to
variadic, we simply add a new overload which takes variadic args:
KStream<K, V> merge(KStream<K, V> first, KStream<K, V>... rest);
That way, we maintain both source *and* binary compatibility for the
existing method, and we can enforce that there is always at least one
stream (argument) being merged.
I'm fine dropping the static methods. As you said, this is mostly all just
syntax sugar anyway, but I do think allowing multiple streams to be merged
together is a benefit. My motivation was that we generate diagrams for our
Topologies, and having several binary merges becomes quite messy when a
single n-ary merge is what you're really modelling.
Regards,
Nick
On Thu, 24 Mar 2022 at 21:24, Matthias J. Sax <mj...@apache.org> wrote:
Thanks for proposing this KIP.
I feel a little bit torn by the idea. In general, we try to keep the
surface area small, and only add APIs that delivery (significant) value.
It seems the current proposal is more or less about syntactic sugar,
what can still be valuable, but I am not really sure about it.
I am also wondering, if we could use a variadic argument instead of a
`Collection`:
KStream<K, V> merge(KStream<K, V>... streams);
This way, we could just replace the existing method in a backward
compatible way (well, source code compatible only) and thus not increase
the surface area of the API while still achieving your goal?
A `merge()` with zero argument would just be a no-op (same as for using
`Collection` I assume?).
For adding the static methods: It seems not to be a common pattern to
me? I might be better not to add them and leave it to users to write a
small helper method themselves if they have such a pattern?
-Matthias
On 1/31/22 7:35 AM, Nick Telford wrote:
Hi everyone,
I'd like to discuss KIP 819:
https://cwiki.apache.org/confluence/display/KAFKA/KIP-819%3A+Merge+multiple+KStreams+in+one+operation
This is a simple KIP that adds/modifies the KStream#merge API to enable
many streams to be merged in a single graph node.
Regards,
Nick Telford
