The .source and .line directives are used primarily when you're using Oolong as an intermediate stage between a program in some other language and the class file. If you're writing Oolong by hand, the Oolong compiler's -n directive will cause .source and .line directives to be generated automatically. Line debugging information will be generated for each instruction, naming the source line of that instruction in the Oolong source file. The .var directive can be used as before to assign names to local variables.
If you provide debugging information, you can use existing debuggers to debug Oolong programs. For example, Figure 7.1 shows Symantec Café version 1.8 debugging an Oolong program.
Figure 7.1. Symantec Café debugging an Oolong program