;------------------------------------------------------------
;------------------------------------------------------------
;------------------------------------------------------------
;+
; NAME:isafile
;
; PURPOSE:find a file and check if it is a real file!
;
; CATEGORY:for open
;
; CALLING SEQUENCE:filename = isafile()
; 
; INPUTS:none
;
; KEYWORD PARAMETERS:
;       FILENAME: a proposed filename.
;       IODIRECTORY: a directory where must be the file.
;       /NEW:to specify that filename is a new file
;
; OUTPUTS:the filename
;
; COMMON BLOCKS:none
;
; SIDE EFFECTS:
;
; RESTRICTIONS:
;
; EXAMPLE:
;
; MODIFICATION HISTORY:Sebastien Masson (smasson@lodyc.jussieu.fr)
;                      11/2/2000
;-
;------------------------------------------------------------
;------------------------------------------------------------
;------------------------------------------------------------
FUNCTION isafile, FILENAME = filename, IODIRECTORY = iodirectory, FILTER = filter, NEW = new
;------------------------------------------------------------
; we find the filename.
;------------------------------------------------------------
; is filename given by the FILENAME keyword a good one?
; si iodirectory n''est pas definit on l''initialise au repertoire courant
   if NOT keyword_set(filename) then filename = 'nimportequoi'
   thisOS = strupcase(strmid(!version.os_family, 0, 3))
   CASE thisOS OF 
      'MAC':sep = ':'
      'WIN':sep = '\'
      ELSE:sep = '/'
   ENDCASE
; we complete filename by iodirectory?
   if strpos(filename, sep) EQ -1 then begin
      if NOT keyword_set(iodirectory) then cd, current = iodirectory
; si iodirectory ne finit pas par sep on le rajoute
      if rstrpos(iodirectory, sep) NE strlen(iodirectory)-1 then $
       iodirectory = iodirectory+sep
      filename = iodirectory+filename
   ENDIF
   if keyword_set(new) then return, filename
   test = findfile(filename)    ; le nom cherche correspond bien a un fichier?
   while test[0] EQ '' OR n_elements(test) GT 1 do BEGIN ; on en cherche un tant qu''il ne correspond a rien!
      test = test[0]
      if keyword_set(filter) AND thisOS NE 'MAC' AND thisOS NE 'WIN' then $
       filename = dialog_pickfile(path = iodirectory, filter = filter) $
       ELSE filename = dialog_pickfile(path = iodirectory)
      if filename EQ '' then return, report('read_data canceled')
      test = findfile(filename)
   endwhile

   return, filename
end