Recover in Fortran

Fortran doesn’t have built-in exception handling or panic recovery mechanisms like Go. However, we can simulate similar behavior using error flags and subroutines. Here’s an example that demonstrates a concept similar to recover in Fortran:

program recover_example
    implicit none
    
    call main()
    
contains

    subroutine may_panic()
        print *, "Simulating a panic"
        call exit(1)  ! Abruptly terminate the program
    end subroutine may_panic
    
    subroutine recover(status)
        integer, intent(out) :: status
        
        ! Fortran doesn't have a built-in recover mechanism
        ! We'll use this subroutine to simulate recovery
        print *, "Recovered. Error: simulated panic"
        status = 0  ! Reset status to indicate successful recovery
    end subroutine recover
    
    subroutine main()
        integer :: status
        
        status = 1  ! Initialize status to error state
        
        ! In Fortran, we can't defer execution, so we'll check the status after the call
        call may_panic()
        
        if (status /= 0) then
            call recover(status)
        end if
        
        ! This code will run if recover is successful
        if (status == 0) then
            print *, "After may_panic()"
        end if
    end subroutine main

end program recover_example

In this Fortran example, we’ve simulated the concept of panic and recover:

1. The may_panic subroutine simulates a panic by calling exit(1), which abruptly terminates the program.

2. The recover subroutine simulates recovery by printing a message and resetting the status flag.

3. In the main subroutine, we call may_panic(). In a real scenario, this would terminate the program.

4. After the call to may_panic(), we check the status. If it’s non-zero (indicating an error), we call recover.

5. If recovery is successful (status is reset to 0), we print “After may_panic()”.

To run this Fortran program:

$ gfortran recover_example.f90 -o recover_example
$ ./recover_example
Simulating a panic

Note that in this simulation, the program will actually terminate when may_panic is called, so you won’t see the “Recovered” message. In a real Fortran program, you would need to implement your own error handling mechanism, possibly using error codes or status flags, to achieve behavior similar to Go’s panic and recover.

Fortran doesn’t have built-in exception handling, so the concept of panic and recover doesn’t directly translate. In practice, Fortran programs typically use error codes or status flags to indicate and handle exceptional conditions.