Obtaining class bytecode about modlauncher

[cpw]

I don't understand your ask here.

[Mumfrey]

Looking through the other issues here, this is basically a corollary (or possibly duplicate) of #4, though with a slightly narrower scope.

It actually boils down to two actualy where Mixin needs to obtain bytecode for a class without actually classloading it, but does need that bytecode to be transformed "normally" by everything except itself. (Using bytecode/classnode interchangably here since the format doesn't matter to me). The two cases are:

1. Obtaining classnode for a "template" class. This is a class which shouldn't be classloaded, it is used as a template for other things. This includes actual mixin bytecode to be loaded, parsed, and applied to targets as well as inner classes of those mixins which need to be synthesized into new versions for the target classes to use. For example if a mixin has an inner class MyMixin$MyInnerClass that "class" must not be loaded, it will be loaded as MixinTarget$RepatriatedInnerClass or OtherMixinTarget$RepatriatedInnerClass and never as its original self. This means the original code passes through the transformer chain once, like it would under a normal class load operation but it never makes it as far as the ClassLoader.

2. Obtaining classnode for an arbitrary class to generate metadata for it. This is because the pipeline is such that a bunch of things in the class hierarchy need to be known before a mixin is applied, but if we wait until class load to obtain those data then it's too late to do anything with them. This includes enumerating fields, methods and interfaces on target classes. Since additional fields, methods and interfaces might be added by transformers - or of course removed - this bytecode needs to travel through the transformer chain as well. This doesn't happen for every class, only classes referenced by mixins.

The ask here is that there isn't an elegant way to obtain the bytecode and run the transformer chain on it without the kind of ugly hacks that I've wrapped in Internals which

• Obtain the original bytecode in a mundane way
• Pass it through the transformer chain with simple reflection
• Short-circuit the transformer chain by throwing an exception

Which works but is somewhat inelegant.

The duties in question are handled by IClassBytecodeProvider so you can see the duties required here.

Hopefully that makes more sense? I'll be around this evening anyway if you want to discuss it some more.