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Re: Sys.argv with interpreter and compiler
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Date: -- (:)
From: Markus Mottl <mottl@m...>
Subject: Re: Sys.argv with interpreter and compiler
> > Wouldn't it be logically more consistent to pass the truncated array
> > of arguments to the script under the interpreter so that the program
> > always gets its name on index 0 - no matter whether it is compiled
> > or interpreted?
> 
> Yes, it would be more consistent, but that's exactly what it does
> currently.  At least, that's what a quick test under Linux shows.
>
> > - With the current version it gets the name of the
> > interpreter on this position.
> 
> That's surprising.  On which operating system do you see this
> behavior?  The treatment of argv[0] in C w.r.t. #! scripts differs
> between various versions of Unix, but we tried to compensate for this
> in the OCaml bytecode interpreter.

My explanation may probably be misconceived - maybe "interpreted" means
"interpreted by the byte code interpreter" to you whereas I use "compiled"
for byte code and native code and "interpreted" if I call the interactive
toplevel with a file argument.

Anyhow, I have made a test on two systems (Intel/Linux and Alpha/Digital
Unix) with ocaml-2.02-2. Both systems behaved exactly the same way, but
I got three different outputs for the three ways to execute the program.

The output of this program (bla.ml):

  print_endline Sys.argv.(0)

yielded:

interpreted:             /home/mottl/mysys/bin/ocaml
compiled to byte code:   ./bla
compiled to native code: bla

The difference between the byte code and native code version is probably
not so big a problem. But it would be useful for the development process
if the "interpreted" version would pass the arguments at the same index
in the argument vector.

As far as I remember, making OCaml (at least under Unix) a "true"
scripting-language (=with human-readable "#!"-scripts) is not so easy to
achieve: only binaries may be used as interpreters of "#!"-scripts, which
is not currently possible with the way the toplevel "ocaml" is designed -
it needs to be a byte code file. Are there already any convenient ways
around this problem?

Using byte code for scripting is not so comfortable and I think that
OCaml would give a wonderful language for "true" scripting...

Best regards,
Markus Mottl

-- 
Markus Mottl, mottl@miss.wu-wien.ac.at, http://miss.wu-wien.ac.at/~mottl