OpenEuphoria

Re: Euphoria environment variables (was: quick cgi question)

• Posted by Juergen Luethje <j.lue at gmx.de> Apr 02, 2006
• 503 views

Ed Davis wrote:

> Juergen Luethje wrote:
> 
>> The interpreter/translator just had to look for a file "Euphoria.ini"
>> in the same directory where it is located itself. 100%
>> cross-platform, and no hassle with environment variables any more.
>> What do you think?
> 
> But is this cross-platform?
> 
> Under DOS and Windows, C compilers use argv[0] to get the complete path
> to the program.
> 
> However, argv[0] isn't populated the same way under Linux. argv[0]
> appears to contain the command string that was typed to start the
> executable.  This is on RedHat, SlackWare, and Knoppix.  I assume the
> other distributions are the same?
> 
> I don't know about FreeBSD, but I assume this is a Unix thing.
> 
> So, how does a program find the complete path to itself on Linux?

I don't know how this would work with C, but fortunately the Euphoria
interpreter front-end and translator are written in Euphoria now. 

-- tested with Eu 2.5 on Windows
-- (should work on all supported platforms)

include misc.e                       -- for constant LINUX

function path_end (sequence name, integer slash)
   for i = length(name) to 1 by -1 do
      if name[i] = slash then
         return i
      end if
   end for
   return find(':', name)
end function

function file_path (sequence name, integer slash)
   -- in : name : filename, e.g. "c:\\programs\\nicetool.exe"
   --      slash: slash charecter in use
   -- out: path, always with trailing slash or colon
   integer p

   p = path_end(name, slash)
   if p = length(name) or name[p+1] != '.' then
      return name[1..p]
   else
      return name & slash
   end if
end function

function prog_path ()
   -- out: full path where this program itself is located,
   --      always with trailing slash or colon
   sequence cmd
   integer slash

   cmd = command_line()
   if platform() = LINUX then
      slash = '/'
   else
      slash = '\\'
   end if
   return file_path(cmd[2], slash)
end function

constant INI_NAME = "euphoria.ini"   -- we can choose this name freely

sequence ini_file
ini_file = prog_path() & INI_NAME    -- full pathname of the INI file
puts(1, ini_file)                    -- ( which is needed e.g for open() )
if getc(0) then end if

> Finally, I agree, it would be nice to not require environment
> variables!

Thanks! Since several people now had said that they share this opinion,
it shows me that the idea was not too crazy. 

Regards,
   Juergen