RPG Cafe: Spring 2022: New messaging opcodes SND-MSG and ON-EXCP

Content

Spring: New messaging opcodes

• SND-MSG: Send an info or escape message
• ON-EXCP: Monitor for a specific message ID

Details

ON-EXCP

Use the ON-EXCP opcode to monitor for a specific message ID. The ON-EXCP opcodes precede any ON-ERROR opcodes in your monitor group.

By default, ON-EXCP can monitor for an unhandled escape message sent to a program or procedure called from the monitor block. If you want to monitor only for messages sent directly to the procedure containing the monitor group, you can specify ON-EXCP(C).

          monitor;
             create_new_account ();
          on-excp 'ARV0203' : 'ARV0204';
             // handle two ARV messages
          endmon;

SND-MSG

Use the SND-MSG opcode to send an informational or escape message. The message type defaults to *INFO.

In the joblog, the "sender" information for the message indicates the procedure and statement number where the message was sent.

The message can be

• A string

            SND-MSG 'Unexpected error';
  

• The %MSG built-in function

            arv0203_reptext.badFile = filename;
            arv0203_reptext.badIdno = id_no;
            SND-MSG %MSG ('ARV0203' : 'ARVMSGS' : arv0203_reptext);
  

By default, an informational message is sent to the current procedure and an escape message is sent to the caller of the current procedure. You can use %TARGET to control where the message is sent.

1. The first operand is the target invocation on the program stack.
2. The second optional operand is the "stack offset" from that invocation. It defaults to zero. For example, a value of 1 indicates that you want to send the message to the caller of the specified invocation. A value of 2 indicates that you want to send the message to the caller's caller.

          // Send a message to the caller of our main procedure
          // - stack offset = 2 since the "caller" is actually the
          //   PEP for the program
          SND-MSG *ESCAPE 'Unexpected customer type ' + type
                           %TARGET('ARVMAIN' : 2);

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