2 Replies Latest reply on Jan 14, 2016 4:42 AM by Andrew Dinn

    Can we insert any java statement/bytecode at any position using ByteMan

    mahesh shet Newbie

      Hi,

       

      Byteman is a awesome tool. I understand we can modify the variable values, throw exceptions etc using ByteMan. Just wanted to understand if there is a way to insert any java statement or equivalent bytecode anywhere in the final code to be executed?

       

      Regards

      Mahesh

        • 1. Re: Can we insert any java statement/bytecode at any position using ByteMan
          James Livingston Apprentice

          Hi Mahesh,

           

          You can't insert arbitrary java statements directly, but you can create a custom helper class which you specify via HELPER with the code, and then insert a call to it in your DO line. See "User-Defined Rule Helpers" in the Programmers Guide.

          • 2. Re: Can we insert any java statement/bytecode at any position using ByteMan
            Andrew Dinn Master

            Hi Mahesh,

             

            As James said there are some limitations on what can go into the DO clause of a rule. You can use all the usual Java expressions apart from control flow statements i.e.

             

              if statements

              while statements

              for statements

              try+catch statements

             

            You can insert more than one expression in a DO clause so long as you separate them using a ';' -- for example

             

            RULE
            ...  
            DO traceln("rule fired");
               traceStack()
            ENDRULE
            

             

            To answer the second half of your question: no, you cannot insert a rule at any position in a Java method but you can insert in most places that are interesting. The list of location (AT) clauses is restricted to positions in the source code which clearly identify locations in the corresponding bytecode. For example

             

            • AT ENTRY
            • AT EXIT
            • AT INVOKE calledMethod
            • AT WRITE fieldName =
            • AT READ $localVarName
            • AT LINE nnn

             

            Some of these locations take a count to identify which  of several calls, reads, writes etc you are interested in (or ALL to inject at every occurence)

             

            If you want to see the full list of all the expressions which can be written into a rule bindings, condition or action clause (including all the default Helper methods) and all the terms  you can employ in a location clause everything is fully documented in the Programmer's Guide.