Allow Java classes to be extended by guest languages

[hymanroth]

Feature request

Jruby allows additional attributes and methods to be added to a Java class. We are considering porting a large project from JRuby to Graal/Truffle but we have thousands of lines of legacy code which depend on Java classes which have been extended (monkey patched) using JRuby.

See this stackoverflow question I posted which includes examples: https://stackoverflow.com/questions/76567012/extending-monkey-patching-java-classes-in-truffle-ruby

If, for technical reasons, it is not possible for Java classes to be extended I would be very grateful if someone could suggest a workaround because right now we're stuck.

I imagine this issue could cause problems for other people trying to port projects from Jruby....

Thanks.

[oubidar-Abderrahim]

Hi, Thank you for your suggestion, we'll take a look into it shortly

[eregon]

Let's track this in oracle/truffleruby#3139
I think this cannot reasonably be solved in Truffle, or not only, so better to track it as a TruffleRuby issue.