Deprecate docstring and update references

Author: oscargus

doc/api/next_api_changes/deprecations/22148-OG.rst

@@ -0,0 +1,5 @@
+Module ``docstring`` deprecated
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The module ``matplotlib.docstring`` is considered internal and public access
+is deprecated.

doc/api/prev_api_changes/api_changes_3.5.0/removals.rst

@@ -214,7 +214,7 @@ The following class methods have been removed:
 - ``Colorbar.on_mappable_changed`` and ``Colorbar.update_bruteforce``; use
   ``Colorbar.update_normal()`` instead
 - ``docstring.Substitution.from_params`` has been removed; directly assign to
-  ``params`` of `.Substitution` instead
+  ``params`` of ``docstring.Substitution`` instead
 - ``DraggableBase.artist_picker``; set the artist's picker instead
 - ``DraggableBase.on_motion_blit``; use `.DraggableBase.on_motion` instead
 - ``FigureCanvasGTK3._renderer_init``

doc/devel/documenting_mpl.rst

@@ -684,14 +684,14 @@ are:
 2. as automated as possible so that as properties change, the docs
    are updated automatically.
 
-The ``@docstring.interpd`` decorator implements this.  Any function accepting
+The ``@_docstring.interpd`` decorator implements this.  Any function accepting
 `.Line2D` pass-through ``kwargs``, e.g., `matplotlib.axes.Axes.plot`, can list
 a summary of the `.Line2D` properties, as follows:
 
 .. code-block:: python
 
   # in axes.py
-  @docstring.interpd
+  @_docstring.interpd
   def plot(self, *args, **kwargs):
       """
       Some stuff omitted
@@ -726,7 +726,7 @@ gets interpolated into the docstring.
 
 Note that this scheme does not work for decorating an Artist's ``__init__``, as
 the subclass and its properties are not defined yet at that point.  Instead,
-``@docstring.interpd`` can be used to decorate the class itself -- at that
+``@_docstring.interpd`` can be used to decorate the class itself -- at that
 point, `.kwdoc` can list the properties and interpolate them into
 ``__init__.__doc__``.
 

lib/matplotlib/__init__.py

@@ -106,7 +106,7 @@
 
 # cbook must import matplotlib only within function
 # definitions, so it is safe to import from it here.
-from . import _api, _version, cbook, docstring, rcsetup
+from . import _api, _version, cbook, _docstring, rcsetup
 from matplotlib.cbook import sanitize_sequence
 from matplotlib._api import MatplotlibDeprecationWarning
 from matplotlib.rcsetup import validate_backend, cycler
@@ -593,7 +593,7 @@ def gen_candidates():
 _deprecated_remain_as_none = {}
 
 
-@docstring.Substitution(
+@_docstring.Substitution(
     "\n".join(map("- {}".format, sorted(rcsetup._validators, key=str.lower)))
 )
 class RcParams(MutableMapping, dict):

lib/matplotlib/_enums.py

@@ -11,7 +11,7 @@
 """
 
 from enum import Enum, auto
-from matplotlib import docstring
+from matplotlib import _docstring
 
 
 class _AutoStringNameEnum(Enum):
@@ -181,5 +181,5 @@ def demo():
         + ", ".join([f"'{cs.name}'" for cs in CapStyle]) \
         + "}"
 
-docstring.interpd.update({'JoinStyle': JoinStyle.input_description,
+_docstring.interpd.update({'JoinStyle': JoinStyle.input_description,
                           'CapStyle': CapStyle.input_description})