read_source_config Subroutine

  subroutine read_source_config(self)
    use file_utils, only: input_unit_exist, get_indexed_namelist_unit
    use mp, only: proc0
    implicit none
    class(source_config_type), intent(in out) :: self
    logical :: exist
    integer :: in_file

    ! Note: When this routine is in the module where these variables live
    ! we shadow the module level variables here. This is intentional to provide
    ! isolation and ensure we can move this routine to another module easily.    
    character(len = 20) :: source_option
    real :: gamma0, omega0, phi_ext, source0, t0

    namelist /source_knobs/ gamma0, omega0, phi_ext, source0, source_option, t0

    ! Only proc0 reads from file
    if (.not. proc0) return

    ! First set local variables from current values
    gamma0 = self%gamma0
    omega0 = self%omega0
    phi_ext = self%phi_ext
    source0 = self%source0
    source_option = self%source_option
    t0 = self%t0

    ! Now read in the main namelist
    in_file = input_unit_exist(self%get_name(), exist)
    if (exist) read(in_file, nml = source_knobs)

    ! Now copy from local variables into type members
    self%gamma0 = gamma0
    self%omega0 = omega0
    self%phi_ext = phi_ext
    self%source0 = source0
    self%source_option = source_option
    self%t0 = t0

    self%exist = exist
  end subroutine read_source_config