Redefining modules in VS Code

Tooling VS Code
1

I have a tiny file defining a module:

module A
using Dates: now
println("Module $(@__MODULE__) defined at $(now())")
end

If I do Julia: Execute File three times, the REPL output is like so:

Module Main.A defined at 2020-11-11T07:32:24.427
Main.A

WARNING: replacing module A.
Module Main.A.A defined at 2020-11-11T07:32:30.564
Main.A.A

WARNING: replacing module A.
Module Main.A.A defined at 2020-11-11T07:35:32.017
Main.A.A

I find this really confusing! Several questions:

  1. On the second execution of the file, why is module Main.A.A defined, rather than Main.A re-defined?
  2. Given that Main.A.A is defined, why is there also a warning about replacing module A? Isn’t Main.A left intact?
  3. Why does the third execution of the file not define Main.A.A.A?

Very frequently I’ll execute a file which defines module A, do some interactive work in the REPL, modify the file, re-execute, and find that for continued REPL work with the updated file, I actually need A_for_real = Main.A.A. Which always surprises me, would love to learn why this happens.

2

That’s an unfortunate bug. We determine the module we’re going to evaluate the file in by looking at the (0,1) position in the text document (which is a hacky fix for other issues), so in this case

m|odule A

This obviously returns A as the containing module, instead of e.g. Main. The first time around A doesn’t exist, so we fall back to Main. The second time (and every time after that) we just replace A.A. AFAICT looking at (0,0) instead has the same issue.

A quick hack around this is to insert something before the module statement, e.g. a new line or a comment or whatever.
I’ll look into fixing that soon(-ish) though.

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