The problem is basically that you select codepages compile time. All the small ones are included by default but a few are left out, eg japanses which are really big, and the UTF-16 stuff that I dont much like anyways. But its there for anyone who wants it.
The string conversion functions are normal functions where the code page is an atom parameter, executed runtime. So its not easy with the current structure to make sure that any necessary codepages are automatically compiled.
If we made each codepage a module, you would need to implement your own «codepage name» to codepage module. This is maybe the best solution, but I cant see a way to make that compatible with the existing library.
I thought about the empty module functionality, but this is in reality not much different from the current functionality, with an additional runtime description added. This would be an improvement over the current code.
The solution we have is basically ok, except mix will not compile if you change the config (this is my understanding though I have not had time to look into this in detail).
Perhaps we should search for solutions in mix? perhaps a sort of callback function in a module that triggers recompilation compile time? One solution could be that any library could generate a hash value based on the mix.exs condiguration and any other external assets, then mix would recompile every time the hash value changes
