ASM incompatible changes

ObjectWeb ASM is a great library that's used to parse Java class files. It's used in all kinds of projects, such as Hibernate, Corba, JAX-WS, Jersey, Spring, Hudson, to name a few. But I have a pet peeve to this otherwise great library, namely its insistence on small size (which by itself isn't a bad thing), and its consequences. One of the choices that made to achieve this was to omit the debug information entirely from the class files, including the line number tables. This is unlike every other OSS Java projects. So you can't step through the ASM code from the debugger, your IDE won't offer any assistance while editing, and it generally makes it hard to use. Another choice they made to achieve the small size is to ignore the backward compatibility. Whenever ASM changes, and it has to change every so often (at least every time a class file format changes), it doesn't do anything to keep the existing applications working. For example, from 2.x to 3.x, the ClassReader.accept method, which parses the class file, has changed in an incompatible way. It used to take ClassVisitor and boolean, which was a flag, but in 3.x it needed to take more flags, so they opted for taking an integer as a bit mask. It was entirely possible to retain the backward compatibility by defining the following simple one line method, but no, keeping asm.jar smaller was more important for ASM, so they just removed the method inste...

Date: February, 12 2010
Url: http://www.java.net/blog/kohsuke/archive/2010/02/12/asm-incompatible-changes

Others News