Extension methods have been available in C# since C# 3.0 (released 2007) and a great addition IMHO. In recent .NET versions, especially ASP.NET, they are heavily relied upon for core framework tasks. Wonder why Java never got them officially.
In java, this would be a compile time problem, because once the class is compiled the extension method is called with `invokestatic` rather than `invokevirtual` used by class methods.
There is also a healthy fear of change in the java community that could explain it.
There is also a healthy fear of change in the java community that could explain it.
This also explains why it took so long for Java to get lambdas. And, generics with primitive types, e.g., ArrayList<int>, via Project Valhalla. It is a super hard problem to upgrade Java without breaking old stuff. Hence, it is a multi-year R&D effort.
I think you can’t look at the past 5 years and the features that are being floated for Java 21 and future releases and think fear of change is the issue—the language is now changing rapidly.
I like his use of the word should, because as we all know it really means won't. I should exercise more, I should stop trolling people on reddit. API designers should control their APIs.
As for the technical objections, I think the conflict-management rules hold the most weight, but this problem is no more difficult than any other in language design. "not overrideable" is a feature, not a bug (can we please give up on behavioural inheritance already?), and discoverability already sucks. I mean, I still use duckduckgo to find javadocs.