+1

TypeInformation has too many methods that need to be implemented but provide little benefit for Flink.


Am 16.05.18 um 10:55 schrieb Ted Yu:
+1 from me as well.

I checked a few serializer classes. The `equals` method on serializers
contains the logic of `canEqual` method whose existence seems redundant.

On Wed, May 16, 2018 at 1:49 AM, Tzu-Li (Gordon) Tai <tzuli...@apache.org>
wrote:

+1.

Looking at the implementations of the `canEqual` method in several
serializers, it seems like all that is done is a check whether the object
is of the same serializer class.
We’ll have to be careful and double check all `equals` method on
serializers that may have relied on the `canEqual` method to perform the
preliminary type check.
Otherwise, this sounds good.

On 16 May 2018 at 4:35:47 PM, Stephan Ewen (se...@apache.org) wrote:

Hi all!

As part of an attempt to simplify some code in the TypeInfo and
TypeSerializer area, I would like to drop the "canEqual" methods for the
following reason:

"canEqual()" is necessary to make proper equality checks across
hierarchies
of types. This is for example useful in a collection API, stating for
example whether a List can be equal to a Collection if they have the same
contents. We don't have that here.

A certain type information (and serializer) is equal to another one if
they
describe the same type, strictly. There is no necessity for cross
hierarchy
checks.

This has also let to the situation that most type infos and serializers
implement just a dummy/default version of "canEqual". Many "equals()"
methods do not even call the other object's "canEqual", etc.

As a first step, we could simply deprecate the method and implement an
empty default, and remove all calls to that method.

Best,
Stephan


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