[FLINK-19892] Replace __metaclass__ field with metaclass keyword

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.12.0, 1.11.3
• Component/s: API / Python
• Labels: pull-request-available
• Assignee: Nicholas Jiang
• Reporter: Huang Xingbo
• Created: 30/Oct/20 06:21
• Updated: 31/Oct/20 01:32
• Resolved: 31/Oct/20 01:32

Description

_metaclass_ is not compatible in some scenarios of python3 e.g.

 

>>> from pyflink.serializers import Serializer
>>> import inspect
>>> inspect.isabstract(Serializer)
False

 

We can replace _metaclass_ field with metaclass keyword to solve these problem. 

Issue Links

• links to: GitHub Pull Request #13856