DOC: Add a warning on methods to access Tick parts (lines, labels, grid)

API docs in the same spirit as matplotlib#31682.

Author: timhoffm

lib/matplotlib/axis.py

@@ -1551,7 +1551,18 @@ def draw(self, renderer):
         self.stale = False
 
     def get_gridlines(self):
-        r"""Return this Axis' grid lines as a list of `.Line2D`\s."""
+        """
+        Return this Axis' grid lines as a list of `.Line2D`.
+
+        .. warning::
+
+            Ticks and their constituent parts, including grid lines, are not
+            guaranteed to be persistent. Various operations can create, delete and
+            modify the Tick instances.
+
+            Consider using `.Axis.set_tick_params` / `.Axis.get_tick_params` to
+            define and query grid styling.
+        """
         ticks = self.get_major_ticks()
         return cbook.silent_list('Line2D gridline',
                                  [tick.gridline for tick in ticks])
@@ -1582,15 +1593,37 @@ def get_pickradius(self):
         return self._pickradius
 
     def get_majorticklabels(self):
-        """Return this Axis' major tick labels, as a list of `~.text.Text`."""
+        """
+        Return this Axis' major tick labels, as a list of `~.text.Text`.
+
+        .. warning::
+
+            Ticks and their constituent parts, including tick labels, are not
+            guaranteed to be persistent. Various operations can create, delete and
+            modify the Tick instances.
+
+            Access to the underlying `.Text` objects is typically not necessary.
+            See the user guide :ref:`user_axes_ticks` for defining and styling ticks.
+        """
         self._update_ticks()
         ticks = self.get_major_ticks()
         labels1 = [tick.label1 for tick in ticks if tick.label1.get_visible()]
         labels2 = [tick.label2 for tick in ticks if tick.label2.get_visible()]
         return labels1 + labels2
 
     def get_minorticklabels(self):
-        """Return this Axis' minor tick labels, as a list of `~.text.Text`."""
+        """
+        Return this Axis' minor tick labels, as a list of `~.text.Text`.
+
+        .. warning::
+
+            Ticks and their constituent parts, including tick labels, are not
+            guaranteed to be persistent. Various operations can create, delete and
+            modify the Tick instances.
+
+            Access to the underlying `.Text` objects is typically not necessary.
+            See the user guide :ref:`user_axes_ticks` for defining and styling ticks.
+        """
         self._update_ticks()
         ticks = self.get_minor_ticks()
         labels1 = [tick.label1 for tick in ticks if tick.label1.get_visible()]
@@ -1601,6 +1634,15 @@ def get_ticklabels(self, minor=False, which=None):
         """
         Get this Axis' tick labels.
 
+        .. warning::
+
+            Ticks and their constituent parts, including tick labels, are not
+            guaranteed to be persistent. Various operations can create, delete and
+            modify the Tick instances.
+
+            Access to the underlying `.Text` objects is typically not necessary.
+            See the user guide :ref:`user_axes_ticks` for defining and styling ticks.
+
         Parameters
         ----------
         minor : bool
@@ -1629,7 +1671,18 @@ def get_ticklabels(self, minor=False, which=None):
         return self.get_majorticklabels()
 
     def get_majorticklines(self):
-        r"""Return this Axis' major tick lines as a list of `.Line2D`\s."""
+        """
+        Return this Axis' major tick lines as a list of `.Line2D`.
+
+        .. warning::
+
+            Ticks and their constituent parts, including tick lines, are not
+            guaranteed to be persistent. Various operations can create, delete and
+            modify the Tick instances.
+
+            Consider using `.Axis.set_tick_params` / `.Axis.get_tick_params` to
+            define and query tick styling.
+        """
         lines = []
         ticks = self.get_major_ticks()
         for tick in ticks:
@@ -1638,7 +1691,18 @@ def get_majorticklines(self):
         return cbook.silent_list('Line2D ticklines', lines)
 
     def get_minorticklines(self):
-        r"""Return this Axis' minor tick lines as a list of `.Line2D`\s."""
+        """
+        Return this Axis' minor tick lines as a list of `.Line2D`.
+
+        .. warning::
+
+            Ticks and their constituent parts, including tick lines, are not
+            guaranteed to be persistent. Various operations can create, delete and
+            modify the Tick instances.
+
+            Consider using `.Axis.set_tick_params` / `.Axis.get_tick_params` to
+            define and query tick styling.
+        """
         lines = []
         ticks = self.get_minor_ticks()
         for tick in ticks:
@@ -1647,7 +1711,18 @@ def get_minorticklines(self):
         return cbook.silent_list('Line2D ticklines', lines)
 
     def get_ticklines(self, minor=False):
-        r"""Return this Axis' tick lines as a list of `.Line2D`\s."""
+        """
+        Return this Axis' tick lines as a list of `.Line2D`.
+
+        .. warning::
+
+            Ticks and their constituent parts, including tick lines, are not
+            guaranteed to be persistent. Various operations can create, delete and
+            modify the Tick instances.
+
+            Consider using `.Axis.set_tick_params` / `.Axis.get_tick_params` to
+            define and query tick styling.
+        """
         if minor:
             return self.get_minorticklines()
         return self.get_majorticklines()
@@ -1774,8 +1849,8 @@ def get_minor_formatter(self):
         return self.minor.formatter
 
     def get_major_ticks(self, numticks=None):
-        r"""
-        Return the list of major `.Tick`\s.
+        """
+        Return the list of major `.Tick`.
 
         .. warning::
 
@@ -1800,8 +1875,8 @@ def get_major_ticks(self, numticks=None):
         return self.majorTicks[:numticks]
 
     def get_minor_ticks(self, numticks=None):
-        r"""
-        Return the list of minor `.Tick`\s.
+        """
+        Return the list of minor `.Tick`.
 
         .. warning::