CLJS-2143

readme.md

Option 1.

https://github.com/Deraen/clojurescript/commit/bb94e566a8827d0356740491e2506fba02faa109

• Load all js_transform.clj files in classpath
• Problems:
  • files are not real namespaces (no ns)
  • load-reader will eval the code in file each time load-js-transforms! is called, which is each time cljs.closure/build is called
  • a js_transform.clj file is loaded even if js-transforms method from it is not needed
    • for example, if any lib in classpath has dep on cljsjs/babel-standalone

Option 2.

https://github.com/Deraen/clojurescript/commit/9866a33c78ebf882e5e01d07316d00c7794e8edc

• If js-transforms method is not found, but the value is namespaced keyword, try to load namespace pointed by the namespace part of the keyword and run js-transforms again in hopes that the namespace provided the method
• If namespace doesn't provide the method, there will be a warning about unsupported preprocess value
• Benefits vs. Option 1:
  • Real namespaces
  • Works with current cljsjs/babel-standalone
  • Minimal change

Option 3?

• :preprocess value should be a symbol
• js-transforms multimethod is removed
• symbol will point directly at a function, the namespace is required if needed
• Benefits:
  • Using a symbol to refer to a function is better than refering to a multimethod using namespaced keyword

Other ideas

• :preprocess should be allowed to be vector of transformations to run?
  • Would be handled at process-js-modules, will work with options 2 and 3

It should be easy to leave the multimethod version around and use that when the value is keyword).

I agree that vector support can be added later, if needed.