A Schema instance is stateful (and contians mutable state) and in the end it contains a reference to the PulsarClient instance that is using it. Look at how AutoConsume schema works for instance.
I don't think it is possible to support such API in the general case. If you want to use it as a key in a map then I suggest you to create a wrapper in your code. Enrico Il Ven 5 Ago 2022, 14:34 Alexander Preuss <alexander.pre...@streamnative.io.invalid> ha scritto: > Hello Pulsar community, > > I would like to start a discussion about PIP 197: Add Schema hash and > equals to public API. > You can find the proposal at https://github.com/apache/pulsar/issues/16959 > as well as pasted below. > > Looking forward to hearing your thoughts, > Alex > > ## Motivation > > Currently, the `Schema` interface in the public client-api does not provide > access to a sensible hash function. The fallback to Java’s object-equality > makes it unfit for use in most hash-based collections. For example, it > prevents usage as a key in a cache. > Further, the lack of a reliable equals function means that there is no way > to identify if two schemas are the same thing. > > ## Goal > > The goal of this proposal is to provide a sensible `hashCode` and `equals` > implementation for Schema as part of the public API. > > Currently, pulsar-common contains `SchemaHash`, a wrapper class that exists > to solve the aforementioned problems. However, `SchemaHash` is not part of > the public API, so users should not depend on it. > > > ## API Changes > > There is no further change required as moving `SchemaHash` from > pulsar-common to the public API. The only further change could be to > re-think the class name, as the wrapper offers more than just a schemas > hash. > > ## Implementation > > Move `SchemaHash` from pulsar-common > `org.apache.pulsar.common.protocol.schema` package into pulsar-client-api > `org.apache.pulsar.common.schema` package. > > > ## Reject Alternatives > > Providing default methods for `equals` and `hashCode` directly on the > `Schema` interface is not possible because Java prohibits overriding the > base Object methods. > Another option would be to provide the `hashCode` and `equals` > functionality through similarly-named default methods that could be used by > any `Schema` implementation. The drawback of this idea is that it requires > developers to override the equals and hashCode to use these provided > methods, as well as possibly polluting the interface. >
