Package org.objectweb.asm.commons

Package org.objectweb.asm.commons Description:

Provides some useful class and method adapters. The preferred way of using these adapters is by chaining them together and to custom adapters (instead of inheriting from them). Indeed this approach provides more combination possibilities than inheritance. For instance, suppose you want to implement an adapter MyAdapter than needs sorted local variables and intermediate stack map frame values taking into account the local variables sort. By using inheritance, this would require MyAdapter to extend AnalyzerAdapter, itself extending LocalVariablesSorter. But AnalyzerAdapter is not a subclass of LocalVariablesSorter, so this is not possible. On the contrary, by using delegation, you can make LocalVariablesSorter delegate to AnalyzerAdapter, itself delegating to MyAdapter. In this case AnalyzerAdapter computes intermediate frames based on the output of LocalVariablesSorter, and MyAdapter can add new locals by calling the newLocal method on LocalVariablesSorter, and can get the stack map frame state before each instruction by reading the locals and stack fields in AnalyzerAdapter (this requires references from MyAdapter back to LocalVariablesSorter and AnalyzerAdapter).