Add type hints to mobject/valuetracker.py

manim/mobject/value_tracker.py

@@ -4,13 +4,19 @@
 
 __all__ = ["ValueTracker", "ComplexValueTracker"]
 
+from typing import TYPE_CHECKING, Any
 
 import numpy as np
 
 from manim.mobject.mobject import Mobject
 from manim.mobject.opengl.opengl_compatibility import ConvertToOpenGL
 from manim.utils.paths import straight_path
 
+if TYPE_CHECKING:
+    from typing_extensions import Self
+
+    from manim.typing import PathFuncType
+
 
 class ValueTracker(Mobject, metaclass=ConvertToOpenGL):
     """A mobject that can be used for tracking (real-valued) parameters.
@@ -69,76 +75,102 @@ def construct(self):
 
     """
 
-    def __init__(self, value=0, **kwargs):
+    def __init__(self, value: float = 0, **kwargs: Any) -> None:
         super().__init__(**kwargs)
         self.set(points=np.zeros((1, 3)))
         self.set_value(value)
 
     def get_value(self) -> float:
         """Get the current value of this ValueTracker."""
-        return self.points[0, 0]
+        value: float = self.points[0, 0]
+        return value
 
-    def set_value(self, value: float):
-        """Sets a new scalar value to the ValueTracker"""
+    def set_value(self, value: float) -> Self:
+        """Sets a new scalar value to the ValueTracker."""
         self.points[0, 0] = value
         return self
 
-    def increment_value(self, d_value: float):
-        """Increments (adds) a scalar value  to the ValueTracker"""
+    def increment_value(self, d_value: float) -> Self:
+        """Increments (adds) a scalar value to the ValueTracker."""
         self.set_value(self.get_value() + d_value)
         return self
 
-    def __bool__(self):
-        """Return whether the value of this value tracker evaluates as true."""
+    def __bool__(self) -> bool:
+        """Return whether the value of this ValueTracker evaluates as true."""
         return bool(self.get_value())
 
-    def __iadd__(self, d_value: float):
-        """adds ``+=`` syntax to increment the value of the ValueTracker"""
-        self.increment_value(d_value)
+    def __iadd__(self, d_value: float | Mobject) -> Self:
+        """adds ``+=`` syntax to increment the value of the ValueTracker."""
+        if isinstance(d_value, Mobject):
+            raise ValueError(
+                "Cannot increment ValueTracker by a Mobject. Please provide a scalar value."
+            )
+        else:
+            self.increment_value(d_value)
         return self
 
-    def __ifloordiv__(self, d_value: float):
-        """Set the value of this value tracker to the floor division of the current value by ``d_value``."""
+    def __ifloordiv__(self, d_value: float) -> Self:
+        """Set the value of this ValueTracker to the floor division of the current value by ``d_value``."""
         self.set_value(self.get_value() // d_value)
         return self
 
-    def __imod__(self, d_value: float):
-        """Set the value of this value tracker to the current value modulo ``d_value``."""
+    def __imod__(self, d_value: float) -> Self:
+        """Set the value of this ValueTracker to the current value modulo ``d_value``."""
         self.set_value(self.get_value() % d_value)
         return self
 
-    def __imul__(self, d_value: float):
-        """Set the value of this value tracker to the product of the current value and ``d_value``."""
+    def __imul__(self, d_value: float) -> Self:
+        """Set the value of this ValueTracker to the product of the current value and ``d_value``."""
         self.set_value(self.get_value() * d_value)
         return self
 
-    def __ipow__(self, d_value: float):
-        """Set the value of this value tracker to the current value raised to the power of ``d_value``."""
+    def __ipow__(self, d_value: float) -> Self:
+        """Set the value of this ValueTracker to the current value raised to the power of ``d_value``."""
         self.set_value(self.get_value() ** d_value)
         return self
 
-    def __isub__(self, d_value: float):
-        """adds ``-=`` syntax to decrement the value of the ValueTracker"""
-        self.increment_value(-d_value)
+    def __sub__(self, d_value: float | Mobject) -> Self:
+        """Decrements the ValueTracker by ``d_value``."""
+        if isinstance(d_value, Mobject):
+            raise ValueError(
+                "Cannot decrement ValueTracker by a Mobject. Please provide a scalar value."
+            )
+        else:
+            self.increment_value(-d_value)
         return self
 
-    def __itruediv__(self, d_value: float):
-        """Sets the value of this value tracker to the current value divided by ``d_value``."""
+    def __isub__(self, d_value: float | Mobject) -> Self:
+        """Adds ``-=`` syntax to decrement the value of the ValueTracker."""
+        if isinstance(d_value, Mobject):
+            raise ValueError(
+                "Cannot decrement ValueTracker by a Mobject. Please provide a scalar value."
+            )
+        else:
+            self.increment_value(-d_value)
+        return self
+
+    def __itruediv__(self, d_value: float) -> Self:
+        """Sets the value of this ValueTracker to the current value divided by ``d_value``."""
         self.set_value(self.get_value() / d_value)
         return self
 
-    def interpolate(self, mobject1, mobject2, alpha, path_func=straight_path()):
-        """
-        Turns self into an interpolation between mobject1
-        and mobject2.
-        """
+    def interpolate(
+        self,
+        mobject1: Mobject,
+        mobject2: Mobject,
+        alpha: float,
+        path_func: PathFuncType = straight_path(),
+    ) -> Self:
+        """Turns ``self`` into an interpolation between ``mobject1`` and ``mobject2``."""
         self.set(points=path_func(mobject1.points, mobject2.points, alpha))
         return self
 
 
 class ComplexValueTracker(ValueTracker):
     """Tracks a complex-valued parameter.
 
+    The value is internally stored as a points array [a, b, 0]. This can be accessed directly
+    to represent the value geometrically, see the usage example.
     When the value is set through :attr:`animate`, the value will take a straight path from the
     source point to the destination point.
 
@@ -161,16 +193,12 @@ def construct(self):
                 self.play(tracker.animate.set_value(tracker.get_value() / (-2 + 3j)))
     """
 
-    def get_value(self):
-        """Get the current value of this value tracker as a complex number.
-
-        The value is internally stored as a points array [a, b, 0]. This can be accessed directly
-        to represent the value geometrically, see the usage example.
-        """
+    def get_value(self) -> complex:  # type: ignore [override]
+        """Get the current value of this ComplexValueTracker as a complex number."""
         return complex(*self.points[0, :2])
 
-    def set_value(self, z):
-        """Sets a new complex value to the ComplexValueTracker"""
-        z = complex(z)
+    def set_value(self, value: complex | float) -> Self:
+        """Sets a new complex value to the ComplexValueTracker."""
+        z = complex(value)
         self.points[0, :2] = (z.real, z.imag)
         return self

mypy.ini

@@ -76,6 +76,9 @@ ignore_errors = False
 [mypy-manim.mobject.geometry.*]
 ignore_errors = True
 
+[mypy-manim.mobject.value_tracker]
+ignore_errors = False
+
 [mypy-manim.renderer.*]
 ignore_errors = True