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C Library Functions  - M_CLI (3)

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NAME

M_CLI(3fm) - [ARGUMENTS:M_CLI::INTRO] command line argument parsing using a prototype command and NAMELIST (LICENSE:PD)

CONTENTS

Synopsis
Description
Examples
Author
License

SYNOPSIS

Usage:

   use M_CLI, only : commandline, check_commandline
   use M_CLI, only : unnamed, debug

DESCRIPTION

Allow for command line parsing much like standard Unix command line parsing using a simple prototype that looks just like a call to the program and NAMELIST.

EXAMPLES

This is an extensive example that even adds a procedure that lets you interactively edit the NAMELIST values. See the demo programs for more basic usage.

Sample program

   program demo_M_CLI
   !-! FULL EXAMPLE ADDING HELP AND VERSION TEXT AND INTERACTIVE EXAMPLE
   use M_CLI,  only : commandline, check_commandline, unnamed
   implicit none
   integer                      :: i
   character(len=:),allocatable :: status
   character(len=255)           :: message ! use for I/O error messages
   character(len=:),allocatable :: readme  ! stores updated namelist
   character(len=:),allocatable :: help_text(:), version_text(:)
   integer                      :: ios

   real               :: x, y, z  ; namelist /args/ x, y, z
   real               :: point(3) ; namelist /args/ point
   character(len=80)  :: title    ; namelist /args/ title
   logical            :: l, l_    ; namelist /args/ l, l_
   character(len=*),parameter :: cmd=&
      ’ -x 1 -y 2 -z 3 --point -1,-2,-3 --title "my title" -l F -L F ’

      !-! PARSING SECTION : SHOULD NOT HAVE TO CHANGE
      call set() !-! set text values for help
      readme=commandline(cmd)
      read(readme,nml=args,iostat=ios,iomsg=message)
      call check_commandline(ios,message,help_text,version_text)
      do
         call readargs(status) ! interactively change NAMELIST group
         if(status.eq.’stop’)exit
         call dosomething() ! use the NAMELIST values
      enddo
      !-! END PARSING SECTION

      !-! ALL DONE CRACKING THE COMMAND LINE.
      !-! USE THE VALUES IN YOUR PROGRAM!

      !-! THE OPTIONAL UNNAMED VALUES ON THE COMMAND LINE ARE
      !-! ACCUMULATED IN THE CHARACTER ARRAY "UNNAMED"
      if(size(unnamed).gt.0)then
         write(*,’(a)’)’files:’
         write(*,’(i6.6,3a)’)(i,’[’,unnamed(i),’]’,i=1,size(unnamed))
      endif

   contains
   subroutine set()
      help_text=[character(len=80) :: &
         ’NAME                                                    ’, &
         ’   myprocedure(1) - make all things possible            ’, &
         ’SYNOPSIS                                                ’, &
         ’   function myprocedure(stuff)                          ’, &
         ’   class(*) :: stuff                                    ’, &
         ’DESCRIPTION                                             ’, &
         ’   myprocedure(1) makes all things possible given STUFF ’, &
         ’OPTIONS                                                 ’, &
         ’   STUFF  things to do things to                        ’, &
         ’RETURNS                                                 ’, &
         ’   MYPROCEDURE  the answers you want                    ’, &
         ’EXAMPLE                                                 ’, &
         ’’ ]

      version_text=[character(len=80) :: &
         ’@(#)PROGRAM:     demo5            >’, &
         ’@(#)DESCRIPTION: My demo program  >’, &
         ’@(#)VERSION:     1.0 20200115     >’, &
         ’@(#)AUTHOR:      me, myself, and I>’, &
         ’@(#)LICENSE:     Public Domain    >’, &
         ’’ ]
   end subroutine set
   subroutine readargs(status)
   character(len=:),intent(out),allocatable :: status
   character(len=256) :: line
   character(len=256) :: answer
   integer            :: lun
   integer            :: ios
      status=’’
      write(*,’(a)’)’args>> "." to run, "stop" to end,&
      & "show" to show keywords, "read","write","sh"’
      do
         write(*,’(a)’,advance=’no’)’args>>’
         read(*,’(a)’)line
         if(line(1:1).eq.’!’)cycle
         select case(line)
          case(’.’)
            exit
          case(’show’)
            write(*,*)’SO FAR’
            write(*,nml=args)
            !-! something where you could restrict nml output to just
            !-! listed names would be nice
            !-!write(*,nml=args)[’A’,’H’]
            !-!write(*,nml=*NML)args[’A’,’H’]
          case(’help’)
          write(*,’(a)’)[character(len=80) :: &
          ’ You are in interactive mode where you can display and change&
          & your values using’, &
          ’ NAMELIST syntax:’, &
          ’  KEYWORD=VALUE(S) - change a variable value’, &
          ’  show             - show current values’, &
          ’  stop             - stop program’, &
          ’  .                - return to program and run’, &
          ’  write FILENAME   - write NAMELIST group to specified file’,&
          ’  read  FILENAME   - read NAMELIST input file’, &
          ’  sh               - start shell process’, &
          ’’, &
         ’’ ]
          case(’stop’)
            status=’stop’
            exit
          case(’sh’)
            call execute_command_line(’bash’)
          case(’read’)
            write(*,’(a)’,advance=’no’)’filename:’
            read(*,’(a)’,iostat=ios)answer
            if(ios.ne.0)exit
            open(file=answer,iostat=ios,newunit=lun)
            if(ios.ne.0)exit
            read(lun,args,iostat=ios)
            close(unit=lun,iostat=ios)
          case(’write’)
            write(*,’(a)’,advance=’no’)’filename:’
            read(*,’(a)’,iostat=ios)answer
            if(ios.ne.0)exit
            open(file=answer,iostat=ios,newunit=lun)
            if(ios.ne.0)exit
            write(lun,args,iostat=ios)
            close(unit=lun,iostat=ios)
          case default
            UPDATE: block
               character(len=:),allocatable :: intmp
               character(len=256)  :: message
               integer :: ios
               intmp=’&ARGS ’//trim(line)//’/’
               read(intmp,nml=args,iostat=ios,iomsg=message)
               if(ios.ne.0)then
                  write(*,*)’ERROR:’,trim(message)
               endif
            endblock UPDATE
         end select
      enddo
   end subroutine readargs
   subroutine dosomething()
      ! placeholder
      write(*,*)’USE ALL THOSE VALUES’
   end subroutine dosomething

   end program demo_M_CLI

AUTHOR

John S. Urban, 2019

LICENSE

Public Domain

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Nemo Release 3.1

M_CLI (3)

February 23, 2025

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