Namespaces should be reloaded after compilation

[ztellman]

I noticed that when I was using the newer version of Virgil, I had to manually reload the namespace before the recompiled class was available. Part of the intended workflow is that the updated classes should be immediately available. It appears that you removed this functionality when doing the refactor, but I assume that was unintentional? If not, we can discuss this further.

[alexander-yakushev]

Hi, thanks for bringing this up! Let me explain my reasoning.

Previous versions of Virgil were Leiningen-centric, and the lein-virgil plugin was the primary driver of the recompilation process. Because the customization options of a plugin are very limited, it made sense to provide namespace reloading out-of-the-box because users didn't have the ability to do it on their own.

The new version of Virgil supports both Leiningen and tools.deps and no longer ships a plugin. Users are expected to control Virgil from the REPL which gives much more flexibility. For example, in the basic case of manually calling virgil/compile-java, the user can include the namespace reloading call like this:

(do (virgil/compile-java ["src"])
    (clojure.tools.namespace.repl/refresh-all))

I think this flexibility is beneficial for several reasons:

• Instead of refresh-all, you can also use refresh or fine-tune the reloading behavior even further. In certain projects where I used Virgil, reloading all namespaces after I recompile a Java class would be inconvenient.
• There is now also https://github.com/tonsky/clj-reload, an alternative code reloading library that gains popularity. Users can decide to use that instead of tools.namespace.

Regarding the automatic Virgil recompilation workflow with virgil/watch-and-recompile, that function has a :post-hook argument where you can trigger reloading:

(virgil/watch-and-recompile ["src"] :post-hook #(clojure.tools.namespace.repl/refresh-all))

Finally, regarding tools.namespace dependency itself. I'm not a fan of bringing unnecessary transitive dependencies, and it is especially so for tools.namespace itself and also for org.clojure/tools.reader which it brings. Both these dependencies are very popular and are prone to causing version conflicts. So, it is better when the user has to provide such dependency explicitly if they need it, and avoid it if they don't need reloading.

[behrica]

Just a question here.
I noticed that I needed sometimes re-execute the "import" statement, usually I do that by re-evaluation the "ns" macro (as it contains the 'import')

Is '(clojure.tools.namespace.repl/refresh-all)' taking care of this as well ?

[alexander-yakushev]

Right, refreshing the namespaces "updates" the class shortname aliases to the newly compiled classes.

[ztellman]

I'm fine with more flexibility, but I'd argue that some sort of auto-refresh is a big part of the ergonomics of the library. I think you should add your comment (or some version thereof) to the README, if that's how you imagine it being used. I completely missed the sentence about :post-hook until just now.