wrap-program –> wrap-script

wrap-program –> wrap-script

[Ricardo Wurmus]

Hi Guix,

I’ve just pushed a change to use wrap-script in one package.  The
purpose of wrap-script is to wrap an executable without having to create
a separate wrapper shell script.  It does this by prepending a Guile
script to the top of the file, which sets the environment variables and
then re-executes itself with the target interpreter (e.g. Python).

I noticed two things:

1) wrap-script does not automatically pull in Guile as a dependency, so
if Guile isn’t among the inputs it will create a bad shebang.  This
should be fixed on core-updates.

2) we aren’t using wrap-script anywhere.  I think a good use case would
be the Python build system’s “wrap” phase where we currently use
wrap-program.  Most of the time we’d be dealing with Python scripts, so
using wrap-script would be more appropriate here.

What do you think?

--
Ricardo

Re: wrap-program –> wrap-script

[Maxim Cournoyer]

Hello Ricardo,

Ricardo Wurmus <rekado@elephly.net> writes:

> Hi Guix,
>
> I’ve just pushed a change to use wrap-script in one package.  The
> purpose of wrap-script is to wrap an executable without having to create
> a separate wrapper shell script.  It does this by prepending a Guile
> script to the top of the file, which sets the environment variables and
> then re-executes itself with the target interpreter (e.g. Python).

That's smart!

> I noticed two things:
>
> 1) wrap-script does not automatically pull in Guile as a dependency, so
> if Guile isn’t among the inputs it will create a bad shebang.  This
> should be fixed on core-

Since as you mention below, the wrap-script isn't much used at all, I
guess the reason to make the change to core-updates rather than master
is because the host module of wrap-script (guix build utils) is used as
a whole when computing the hash of derivations?

> 2) we aren’t using wrap-script anywhere.  I think a good use case would
> be the Python build system’s “wrap” phase where we currently use
> wrap-program.  Most of the time we’d be dealing with Python scripts, so
> using wrap-script would be more appropriate here.
>
> What do you think?

Are you considering "testing" for the type of file (e.g., script?
binary?) before wrapping it?  Something else?

I like the idea in general.  IIUC this would remove the need to have
those ugly .real-script-name lying around.

Maxim

Re: wrap-program –> wrap-script

[Efraim Flashner]

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On Wed, Dec 11, 2019 at 04:57:41PM +0100, Ricardo Wurmus wrote:
> Hi Guix,
> 
> I’ve just pushed a change to use wrap-script in one package.  The
> purpose of wrap-script is to wrap an executable without having to create
> a separate wrapper shell script.  It does this by prepending a Guile
> script to the top of the file, which sets the environment variables and
> then re-executes itself with the target interpreter (e.g. Python).
> 
> I noticed two things:
> 
> 1) wrap-script does not automatically pull in Guile as a dependency, so
> if Guile isn’t among the inputs it will create a bad shebang.  This
> should be fixed on core-updates.

I thought the build systems had an implicit guile in them. Looks like I
had that exactly backwards.

> 
> 2) we aren’t using wrap-script anywhere.  I think a good use case would
> be the Python build system’s “wrap” phase where we currently use
> wrap-program.  Most of the time we’d be dealing with Python scripts, so
> using wrap-script would be more appropriate here.

It turns out we are using it in vpnc-scripts.

-- 
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Re: wrap-program –> wrap-script

[Ricardo Wurmus]

Efraim Flashner <efraim@flashner.co.il> writes:

> On Wed, Dec 11, 2019 at 04:57:41PM +0100, Ricardo Wurmus wrote:
[…]
>> I’ve just pushed a change to use wrap-script in one package. […]
>> 
>> 2) we aren’t using wrap-script anywhere.  I think a good use case would
>> be the Python build system’s “wrap” phase where we currently use
>> wrap-program.  Most of the time we’d be dealing with Python scripts, so
>> using wrap-script would be more appropriate here.
>
> It turns out we are using it in vpnc-scripts.

Yes, that’s where I added it right before writing my email.

-- 
Ricardo

Re: wrap-program –> wrap-script

[Ludovic Courtès]

Hello!

Ricardo Wurmus <rekado@elephly.net> skribis:

> I’ve just pushed a change to use wrap-script in one package.  The
> purpose of wrap-script is to wrap an executable without having to create
> a separate wrapper shell script.  It does this by prepending a Guile
> script to the top of the file, which sets the environment variables and
> then re-executes itself with the target interpreter (e.g. Python).

Neat!

> I noticed two things:
>
> 1) wrap-script does not automatically pull in Guile as a dependency, so
> if Guile isn’t among the inputs it will create a bad shebang.  This
> should be fixed on core-updates.

Or we could say that it’s not different from other shebangs: it’s up to
the packager to provide all the necessary dependencies.

> 2) we aren’t using wrap-script anywhere.  I think a good use case would
> be the Python build system’s “wrap” phase where we currently use
> wrap-program.  Most of the time we’d be dealing with Python scripts, so
> using wrap-script would be more appropriate here.

The would immediately reach hundreds of packages, so it’s a good idea!

Thanks,
Ludo’.