Recover in COBOL

COBOL doesn’t have a direct equivalent to panic and recover mechanisms as in Go. However, we can demonstrate error handling using the ON EXCEPTION clause, which is somewhat similar in concept.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. RECOVER-EXAMPLE.
       ENVIRONMENT DIVISION.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 WS-ERROR PIC X(50).
       
       PROCEDURE DIVISION.
       MAIN-PROCEDURE.
           PERFORM HANDLE-ERROR
           PERFORM MAY-CAUSE-ERROR
           DISPLAY "After MAY-CAUSE-ERROR"
           STOP RUN.

       HANDLE-ERROR.
           DISPLAY "Entering error handling routine."

       MAY-CAUSE-ERROR.
           DISPLAY "Entering MAY-CAUSE-ERROR."
           DIVIDE 1 BY 0
               ON SIZE ERROR
                   MOVE "A problem occurred: Division by zero" 
                        TO WS-ERROR
                   PERFORM RECOVER-FROM-ERROR
           END-DIVIDE.
           DISPLAY "This line will not be executed."

       RECOVER-FROM-ERROR.
           DISPLAY "Recovered. Error:"
           DISPLAY WS-ERROR.

In this COBOL program, we simulate the concept of panic and recover using COBOL’s error handling mechanisms.

The HANDLE-ERROR paragraph is similar to a deferred function in Go. It’s called at the beginning of the MAIN-PROCEDURE, setting up our error handling routine.

The MAY-CAUSE-ERROR paragraph is analogous to the mayPanic function in the Go example. It attempts a division by zero, which will cause an error.

We use the ON SIZE ERROR clause to catch the division by zero error. This is somewhat similar to how recover catches a panic in Go.

In the RECOVER-FROM-ERROR paragraph, we display the error message, similar to how the Go example prints the recovered panic.

To run this COBOL program, you would typically compile it and then execute the resulting binary. The exact commands may vary depending on your COBOL compiler, but it might look something like this:

$ cobc -x recover-example.cob
$ ./recover-example
Entering error handling routine.
Entering MAY-CAUSE-ERROR.
Recovered. Error:
A problem occurred: Division by zero
After MAY-CAUSE-ERROR

Note that unlike in the Go example, the “After MAY-CAUSE-ERROR” message is displayed. This is because COBOL’s error handling allows the program to continue execution after handling an error, whereas Go’s panic mechanism stops the normal flow of the program unless recovered.

While this COBOL example doesn’t provide the exact same behavior as the Go panic/recover mechanism, it demonstrates a similar concept of handling and recovering from errors in COBOL.