Re: change to the wrap-program procedure (was: core-updates, let’s go!)

[Ricardo Wurmus <rekado@elephly.net>]

Hi Hartmut,

> Am 31.12.2017 um 18:27 schrieb Ricardo Wurmus:
>> There’s also a change to the wrap-program procedure that does without
>> the shell wrappers and instead prepends a short Guile program, which is
>> read as a comment in the target language.  It’s better to play with this
>> in the next core-updates cycle.
>
> I assume, this is what we discussed in
> <https://lists.gnu.org/archive/html/guix-devel/2017-11/msg00041.html>.
>
> I just wonder whether this will keep the encoding-lines in place, like
> these:
>
> #!/usr/bin/python
> # -*- coding: latin-1 -*-
> from __future__ import print_function

In the current implementation that I have here it would not.

According to the documentation[1], the regular expression
“coding[=:]\s*([-\w.]+)” must match for a comment on the second line of
a script, so I’d think that the following would still be valid:

--8<---------------cut here---------------start------------->8---
#!/gnu/store/…/bin/guile --no-auto-compile
#!#; -*- coding: latin-1 -*-
#\-(setenv …)
#\-(apply execl …)
#!/gnu/store/…/bin/python3
# -*- coding: latin-1 -*-
…
--8<---------------cut here---------------end--------------->8---

All we need to do is read the second line of the script and see if it is
a coding comment; in that case we’d place the content on the second
line.  I’ll add a special case for this and a test case.  Thanks for
bringing it up!

[1]: https://docs.python.org/3/reference/lexical_analysis.html#encoding-declarations

--
Ricardo

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