A JVM in Rust part 5 – Executing instructions

Rust noob here so please be gentle - can someone explain why in `Vm&lt;&#x27;a&gt;` the lifetime is needed? I see that in tests, `Vm&lt;&#x27;static&gt;` gets created, presumably because there&#x27;s nowhere to grab a better lifetime from? But if that&#x27;s the case, would it be possible to express this in a different way? ISTM that Vm owns everything it needs, so is there a way to avoid bubbling the lifetime up?<p>Similar question applies to ClassManager - it already owns all the classes (they are in an arena), so it looks like a lifetime is needed because there&#x27;s no way to say &quot;things live as long as ClassManager lives&quot; w&#x2F;o introducing the lifetime at `ClassManager&lt;&#x27;a&gt;` level...

Nice and detailed, thanks! As a struggling Rust n00b it&#x27;s instructive with these kinds of walk-throughs.<p>Found a typo: &quot;[...] and the program counter will be implemented.&quot; -- the last word qouted should be &quot;incremented&quot;, right?

Pretty interesting to see the progress on this. Wonder if any of the JVM devs are looking at this, and curious how far it will progress.

When storing an object in an array, the value is checked to be a Value::Object (which can&#x27;t be null), but you also have Value::Null, so storing null in an array fails (I think). Storing null in local variables, a static field or an instance field works fine.

From the first post in the series:<p>&gt; I am very happy with what I have learned, about Rust and about how to implement a virtual machine. In particular, I am super happy about having implemented a real, working, garbage collector. It’s quite mediocre, but it’s mine and I love it. Given that I have achieved what I set out to do originally, I have decided to stop the project here. I know there are bugs, but I do not plan to fix them.<p>Toy projects are fine, but I just think this should be pointed out clearly that this is not a serious, ongoing project.

So can we have a JVM written in Rust, running on WASM, running some Java, running MineCraft?