New Feature: Add generic set method and compatibility layer between properties and get_*/set_* methods (#995)

* Add generic set method, compatibilty layer between properties and get_* and set_* methods

* Fix doctest

* Add docs for the compatibility layer, make sure set_* methods from the layer are indeed methods

* Add newline after ::

* Add DeprecationWarning to the compatibility layer, make DeprecationWarnings show

Author: friedkeenan

manim/mobject/mobject.py

@@ -10,6 +10,8 @@
 import operator as op
 import random
 import sys
+import types
+import warnings
 
 from pathlib import Path
 from colour import Color
@@ -34,6 +36,10 @@
 class Mobject(Container):
     """Mathematical Object: base class for objects that can be displayed on screen.
 
+    There is a compatibility layer that allows for
+    getting and setting generic attributes with ``get_*``
+    and ``set_*`` methods. See :meth:`set` for more details.
+
     Attributes
     ----------
     submobjects : :class:`list`
@@ -248,6 +254,106 @@ def __sub__(self, other):
     def __isub__(self, other):
         raise NotImplementedError
 
+    def set(self, **kwargs):
+        """Sets attributes.
+
+        Mainly to be used along with :attr:`animate` to
+        animate setting attributes.
+
+        In addition to this method, there is a compatibility
+        layer that allows ``get_*`` and ``set_*`` methods to
+        get and set generic attributes. For instance::
+
+            >>> mob = Mobject()
+            >>> mob.set_foo(0)
+            Mobject
+            >>> mob.get_foo()
+            0
+            >>> mob.foo
+            0
+
+        This compatibility layer does not interfere with any
+        ``get_*`` or ``set_*`` methods that are explicitly
+        defined.
+
+        .. warning::
+
+            This compatibility layer is for backwards compatibility
+            and is not guaranteed to stay around. Where applicable,
+            please prefer getting/setting attributes normally or with
+            the :meth:`set` method.
+
+        Parameters
+        ----------
+        **kwargs
+            The attributes and corresponding values to set.
+
+        Returns
+        -------
+        :class:`Mobject`
+            ``self``
+
+        Examples
+        --------
+        ::
+
+            >>> mob = Mobject()
+            >>> mob.set(foo=0)
+            Mobject
+            >>> mob.foo
+            0
+        """
+
+        for attr, value in kwargs.items():
+            setattr(self, attr, value)
+
+        return self
+
+    def __getattr__(self, attr):
+        # Add automatic compatibility layer
+        # between properties and get_* and set_*
+        # methods.
+        #
+        # In python 3.9+ we could change this
+        # logic to use str.remove_prefix instead.
+
+        if attr.startswith("get_"):
+            # Remove the "get_" prefix
+            to_get = attr[4:]
+
+            def getter(self):
+                warnings.warn(
+                    "This method is not guaranteed to stay around. Please prefer getting the attribute normally.",
+                    DeprecationWarning,
+                    stacklevel=2,
+                )
+
+                return getattr(self, to_get)
+
+            # Return a bound method
+            return types.MethodType(getter, self)
+
+        if attr.startswith("set_"):
+            # Remove the "set_" prefix
+            to_set = attr[4:]
+
+            def setter(self, value):
+                warnings.warn(
+                    "This method is not guaranteed to stay around. Please prefer setting the attribute normally or with Mobject.set().",
+                    DeprecationWarning,
+                    stacklevel=2,
+                )
+
+                setattr(self, to_set, value)
+
+                return self
+
+            # Return a bound method
+            return types.MethodType(setter, self)
+
+        # Unhandled attribute, therefore error
+        raise AttributeError
+
     def get_array_attrs(self):
         return ["points"]
 

manim/utils/module_ops.py

@@ -6,6 +6,7 @@
 import sys
 import types
 import re
+import warnings
 
 
 def get_module(file_name: Path):
@@ -33,6 +34,11 @@ def get_module(file_name: Path):
             if ext != ".py":
                 raise ValueError(f"{file_name} is not a valid Manim python script.")
             module_name = ext.replace(os.sep, ".").split(".")[-1]
+
+            warnings.filterwarnings(
+                "default", category=DeprecationWarning, module=module_name
+            )
+
             spec = importlib.util.spec_from_file_location(module_name, file_name)
             module = importlib.util.module_from_spec(spec)
             sys.modules[module_name] = module

tests/test_get_set.py

@@ -0,0 +1,40 @@
+import types
+import pytest
+
+from manim.mobject.mobject import Mobject
+
+
+def test_generic_set():
+    m = Mobject()
+    m.set(test=0)
+
+    assert m.test == 0
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_get_compat_layer():
+    m = Mobject()
+
+    assert isinstance(m.get_test, types.MethodType)
+    with pytest.raises(AttributeError):
+        m.get_test()
+
+    m.test = 0
+    assert m.get_test() == 0
+
+
+@pytest.mark.filterwarnings("ignore::DeprecationWarning")
+def test_set_compat_layer():
+    m = Mobject()
+
+    assert isinstance(m.set_test, types.MethodType)
+    m.set_test(0)
+
+    assert m.test == 0
+
+
+def test_nonexistent_attr():
+    m = Mobject()
+
+    with pytest.raises(AttributeError):
+        m.test