[PATCH] doc: Add guide how to specify dependencies for Python packages

[Hartmut Goebel]

* doc/guix.texi (Python Modules): New sub-subsection "Specifying
  Dependencies".
---
 doc/guix.texi | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/doc/guix.texi b/doc/guix.texi
index 9bd8b43..f51ab75 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -12194,6 +12194,43 @@ starts with @code{py} (e.g. @code{pytz}), we keep it 
and prefix it as
 described above.
 
 
address@hidden Specifying Dependencies
address@hidden inputs, for Python packages
+
address@hidden
+
address@hidden
+All Python package required at run-time need to go into
address@hidden  These are typically defined in
address@hidden or in a requirements-file.
+
address@hidden
+Python packages required only for building (to be found e.g. in
address@hidden) or testing (to be found e.g. in
address@hidden) go into @code{native-inputs}. Examples are
address@hidden, @emph{pytest}, @emph{mock}, and @emph{nose}. Of
+course if any of these packages is required at run-time, it needs to be
+set in @code{propagated-inputs}.
+
address@hidden
address@hidden only contain programs or C-libraries (and such) required
+for building Python packages containing c-extensions (or such).
+
address@hidden
+If a Python package has optional extra dependencies
+(@code{extras_require}), not these are not listed here at all - except
+if there is a test-case in which case they are added to
address@hidden
+
address@hidden
+If a packages has complicated optional extra dependencies you may want
+to define another package to ease resolving these dependencies for the
+user.  E.g. @code{python-abcdef-ssh} inherits @code{python-abcdef} and
+adds the dependencies required for the @emph{ssh} extra feature.
+
address@hidden itemize
+
+
 @node Perl Modules
 @subsection Perl Modules
 
-- 
2.7.4