Re: package dependencies

[Ludovic Courtès]

address@hidden (Ludovic Courtès) skribis:

> Leo Famulari <address@hidden> skribis:
>
>> On Sun, Dec 13, 2015 at 02:45:46PM +0100, Ludovic Courtès wrote:
>>> Hello!
>>> 
>>> I’ve rephrased the doc in “package Reference” in a way that is hopefully
>>> clearer:
>>> 
>>>      ‘inputs’ (default: ‘'()’)
>>>      ‘native-inputs’ (default: ‘'()’)
>>>      ‘propagated-inputs’ (default: ‘'()’)
>>>           These fields list dependencies of the package.  Each one is a
>>>           list of tuples, where each tuple has a label for the input (a
>>>           string) as its first element, a package, origin, or derivation
>>>           as its second element, and optionally the name of the output
>>>           thereof that should be used, which defaults to ‘"out"’ (*note
>>>           Packages with Multiple Outputs::, for more on package
>>>           outputs).  For example, the list below specifies 3 inputs:
>>> 
>>>                `(("libffi" ,libffi)
>>>                  ("libunistring" ,libunistring)
>>>                  ("glib:bin" ,glib "bin"))  ;the "bin" output of Glib
>>> 
>>>           The distinction between ‘native-inputs’ and ‘inputs’ is
>>>           necessary when considering cross-compilation.  When
>>>           cross-compiling, dependencies listed in ‘inputs’ are built for
>>>           the _target_ architecture; conversely, dependencies listed in
>>>           ‘native-inputs’ are built for the architecture of the _build_
>>>           machine.
>>> 
>>>           ‘native-inputs’ is typically where you would list tools needed
>>>           at build time but not at run time, such as Autoconf, Automake,
>>>           pkg-config, Gettext, or Bison.  ‘guix lint’ can report likely
>>>           mistakes in this area (*note Invoking guix lint::).
>>> 
>>>           Lastly, ‘propagated-inputs’ is similar to ‘inputs’, but the
>>>           specified packages will be force-installed alongside the
>>>           package they belong to (*note ‘guix package’:
>>>           package-cmd-propagated-inputs, for information on how ‘guix
>>>           package’ deals with propagated inputs.)
>>> 
>>>           For example this is necessary when a library needs headers of
>>>           another library to compile, or needs another shared library to
>>>           be linked alongside itself when a program wants to link to it.
>>
>> I think it's a good improvement! This is a big obstacle for new
>> packagers.
>>
>> It may be worth linking between the sections about propagated-inputs and
>> the python-build-system, since the situation is somewhat different
>> there. At least in a footnote.
>
> Good point.  How about the patch below?  I’m not sure whether/how to
> cross-reference from ‘python-build-system’ & co. since they don’t
> mention the problem.

Pushed as e0508b6.

Ludo’.