That's why I included the link about Hot and Cold Observables. I suggest you read up on some of the philosophy behind Rx. If you still have questions, you can always ask them on the software engineering stack exchange, or here if they directly relate to code rather than philosophy. — Daniel T. 37 secs ago

This question may be a better fit on Software Engineering SE or Server Fault. — Nathan 52 secs ago

This might be a better fit for the software engineering site, but you make sure it satisfies softwareengineering.stackexchange.com/help/on-topic — snakecharmerb 41 secs ago

Welcome to Stack Overflow (SO). SO is a question and answer page for professional and enthusiast programmers. Please add your own code to your question. You are expected to show at least the amount of research you have put into solving this question yourself. — Cyrus 47 secs ago

Welcome to Stack Overflow. Please take the tour to learn how Stack Overflow works and read How to Ask on how to improve the quality of your question. Then check the help center to see which questions are on-topic on this site. Please see: Why is “Is it possible to…” a poorly worded question? (don't just change your question to "How"). Please show your attempts you have tried and the problems/error messages you get from your attempts. — Progman 43 secs ago

Also please read How do I ask and answer homework questions? as well as Open letter to students with homework problems — Some programmer dude 38 secs ago

...an access made via lvalue whose address is freshly visibly derived from one of a particular type should be recognized as being an access of that type in cases where the latter would be defined, but left the meaning of "freshly visibly derived" as a Quality of Implementation issue, that would be much more workable for programmers and most compiler writers alike, at least for people who aren't having to maintain compilers whose front-ends strip out information necessary to support such constructs. — supercat 16 secs ago

At this point, you're moving past ANTLR's part in building your language. Though, it does provide the Listener and Visitor classes to make it easier to use the parse tree. So far as good reads, Language Implementation Patterns (from Pragmatic Programmers) is written "The ANTLR Guy" Terrence Parr, so it's a good "next step" (just be aware that the ANTLR specific parts have fallen a bit out of date) — Mike Cargal 9 secs ago

The short answer is "It depends, use whichever is clearer and more readable in context." Beyond that, I'm afraid Stack Overflow is expressly not suited for open-ended, opinion-based questions. It would probably be a better fit on Software Engineering, but it may or may not be too open-ended for there too, I'm not sure. — CrazyChucky 39 secs ago

The correct solution is 1/10th of the shown code, in size. Unfortunately sites like leetcode are just random lists of coding puzzles. There's nothing on Leetcode that teaches anyone the fundamentals of C++ and algorithms, and the knowledge needed to do their puzzles. That can only be found in an edited textbook. Programming random coding puzzles is not a very good way to learn C++. Sites like Leetcode are meant for experienced programmers who like to do random conding puzzles in their free time, and it's not meant to be used to learn computer programming. — Sam Varshavchik just now