Title here
Summary here
Enums in Co-array Fortran
Our enum type ServerState has an underlying integer type.
module server_states
implicit none
integer, parameter :: StateIdle = 0
integer, parameter :: StateConnected = 1
integer, parameter :: StateError = 2
integer, parameter :: StateRetrying = 3
contains
function state_name(state) result(name)
integer, intent(in) :: state
character(len=20) :: name
select case (state)
case (StateIdle)
name = 'idle'
case (StateConnected)
name = 'connected'
case (StateError)
name = 'error'
case (StateRetrying)
name = 'retrying'
case default
name = 'unknown'
end select
end function state_name
function transition(s) result(ns)
integer, intent(in) :: s
integer :: ns
select case (s)
case (StateIdle)
ns = StateConnected
case (StateConnected, StateRetrying)
ns = StateIdle
case (StateError)
ns = StateError
case default
print *, 'Error: unknown state'
stop 1
end select
end function transition
end module server_states
program main
use server_states
implicit none
integer :: ns, ns2
ns = transition(StateIdle)
print *, state_name(ns)
ns2 = transition(ns)
print *, state_name(ns2)
end program mainTo compile and run this program, you can use a Fortran compiler like gfortran.
$ gfortran -o server server_states.f90
$ ./server
connected
idleIn this example, we define the possible states of the server using parameters (constants). We have a state_name function to convert the states to strings and a transition function to handle state transitions. The main program demonstrates these by transitioning from StateIdle to StateConnected, then back to StateIdle.