docs: updates related to extensions (#33837)

2 files changed, 8 insertions, 9 deletions

diff --git a/lib/spack/docs/build_systems/pythonpackage.rst b/lib/spack/docs/build_systems/pythonpackage.rst
index 53d0f09167..9be95d1fb9 100644
--- a/lib/spack/docs/build_systems/pythonpackage.rst
+++ b/lib/spack/docs/build_systems/pythonpackage.rst
@@ -724,10 +724,9 @@ extends vs. depends_on
 
 This is very similar to the naming dilemma above, with a slight twist.
 As mentioned in the :ref:`Packaging Guide <packaging_extensions>`,
-``extends`` and ``depends_on`` are very similar, but ``extends`` adds
-the ability to *activate* the package. Activation involves symlinking
-everything in the installation prefix of the package to the installation
-prefix of Python. This allows the user to import a Python module without
+``extends`` and ``depends_on`` are very similar, but ``extends`` ensures
+that the extension and extendee share the same prefix in views.
+This allows the user to import a Python module without
 having to add that module to ``PYTHONPATH``.
 
 When deciding between ``extends`` and ``depends_on``, the best rule of
@@ -735,7 +734,7 @@ thumb is to check the installation prefix. If Python libraries are
 installed to ``<prefix>/lib/pythonX.Y/site-packages``, then you
 should use ``extends``. If Python libraries are installed elsewhere
 or the only files that get installed reside in ``<prefix>/bin``, then
-don't use ``extends``, as symlinking the package wouldn't be useful.
+don't use ``extends``.
 
 ^^^^^^^^^^^^^^^^^^^^^
 Alternatives to Spack
diff --git a/lib/spack/docs/build_systems/rpackage.rst b/lib/spack/docs/build_systems/rpackage.rst
index ebf2270e8e..567b79a863 100644
--- a/lib/spack/docs/build_systems/rpackage.rst
+++ b/lib/spack/docs/build_systems/rpackage.rst
@@ -193,10 +193,10 @@ Build system dependencies
 
 As an extension of the R ecosystem, your package will obviously depend
 on R to build and run. Normally, we would use ``depends_on`` to express
-this, but for R packages, we use ``extends``. ``extends`` is similar to
-``depends_on``, but adds an additional feature: the ability to "activate"
-the package by symlinking it to the R installation directory. Since
-every R package needs this, the ``RPackage`` base class contains:
+this, but for R packages, we use ``extends``. This implies a special
+dependency on R, which is used to set environment variables such as
+``R_LIBS`` uniformly. Since every R package needs this, the ``RPackage``
+base class contains:
 
 .. code-block:: python