Re: avoid wrapper scripts when possible

[ludo@gnu.org (Ludovic Courtès)]

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.  ‘wrap-program’ would grab the shebang and check if the
basename of the interpreter is in that white list.

Thoughts?

Ludo’.