Javassist VS Maker

ClassPool comes from Javaassist library. It gives convenient API to retrieve the line number of Java method.

This problem can be resolved by https://github.com/jboss-javassist/javassist/blob/master/src/main/javassist/util/proxy/DefineClassHelper.java perfectly, I will use some of its code to fix this problem on 0.0.1

Other higher-level abstractions like Javassist: are all based on ASM, but have a nicer and easier-to-understand APIs to deal with.

In the following snippet, the transformer uses Javassist:

If you want an alternative to ASM, try Cojen/Maker, which is designed to be much easier to use than any of the other class writing APIs, including the one proposed by JEP-8280389. Here's a comparison.

That's a lot right arrow operators just to implement a simple Hello World program (5). I can't even begin to imagine how difficult it might be to generate anything more interesting than this. Here's a comparison against a classfile API which is designed to be easy to use: https://github.com/cojen/Maker/wiki/JEP-8280389

For the code generation phase, it might be easier to bypass emitting a text-based assembly format and just use the ASM library directly. If you want something easier, I wrote a code generation library specifically for that purpose: https://github.com/cojen/Maker It also includes an example "Mini-C" language compiler.