From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: avoid wrapper scripts when possible
Date: Sun, 05 Nov 2017 18:06:17 +0100
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In-Reply-To: <65968230-bd78-dfe7-2767-c1b7b89ad748@crazy-compilers.com>
	(Hartmut Goebel's message of "Sun, 5 Nov 2017 12:00:17 +0100")
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To: Hartmut Goebel <h.goebel@crazy-compilers.com>
Cc: guix-devel <guix-devel@gnu.org>

Hi!

Hartmut Goebel <h.goebel@crazy-compilers.com> skribis:

> answering on a mail which Ricardo CCed to me and which did not make it
> to the list yet. Thus I full-quote.
>
> Am 04.11.2017 um 23:30 schrieb Ricardo Wurmus:
>> How about this:
>>
>> --8<---------------cut here---------------start------------->8---
>> #!/home/rekado/.guix-profile/bin/guile --no-auto-compile
>> #!# (let (($0 (car (command-line)))) (execl "/home/rekado/.guix-profile/=
bin/python3" $0 $0))
>> #!/home/rekado/.guix-profile/bin/python3
>> import sys; print("hello from python: "+sys.argv[0])
>> --8<---------------cut here---------------end--------------->8---
>>
>> The first two lines are Guile code, but they are also line comments in
>> shell, Perl, Python, Ruby, and R.  The Guile code in this example calls
>> the script again as a Python script.  Before doing that it can set
>> environment variables, like so:
>>
>> --8<---------------cut here---------------start------------->8---
>> #!/home/rekado/.guix-profile/bin/guile --no-auto-compile
>> #!#
>> #\- (setenv "PYTHONPATH" (string-append "/gnu/store/foo:/gnu/store/bar:"=
 (getenv "PYTHONPATH")))
>> #\- (let (($0 (car (command-line)))) (execl "/home/rekado/.guix-profile/=
bin/python3" $0 $0))
>> #!/home/rekado/.guix-profile/bin/python3
>> import sys; print("hello from python: "+sys.argv[0])
>> print(sys.path)
>> --8<---------------cut here---------------end--------------->8---
>>
>> Did I overlook something?  Or could we use this hack to remove separate
>> wrapper scripts for Perl, Python, Ruby, and R?

Overall this looks good to me (with the adjustments Hartmut mentions).

Now, we should have a white list of languages for which this can be
done.  =E2=80=98wrap-program=E2=80=99 would grab the shebang and check if t=
he
basename of the interpreter is in that white list.

Thoughts?

Ludo=E2=80=99.