Add type annotations to `mobject.py` #4388

henrikmidtiby · 2025-08-10T19:00:58Z

Overview: What does this pull request change?

This PR add type annotations to mobject.py.

Issue #3375.

Reviewer Checklist

The PR title is descriptive enough for the changelog, and the PR is labeled correctly
If applicable: newly added non-private functions and classes have a docstring including a short summary and a PARAMETERS section
If applicable: newly added functions and classes are tested

…2282

… code for the remaning 10 errors

henrikmidtiby · 2025-08-10T20:00:10Z

manim/mobject/geometry/line.py

+            # error: Argument "tip" to "add_tip" of "TipableVMobject" has incompatible type "VMobject"; expected "ArrowTip | None"  [arg-type]
            self.add_tip(tip=old_tips[0])
        if has_start_tip:
+            # error: Argument "tip" to "add_tip" of "TipableVMobject" has incompatible type "VMobject"; expected "ArrowTip | None"  [arg-type]
            self.add_tip(tip=old_tips[1], at_start=True)


These issues can be handled by typing.cast, but I don't think that is the best way to deal with them.

henrikmidtiby · 2025-08-10T20:02:48Z

manim/mobject/types/vectorized_mobject.py

+    def __getitem__(self, key: int) -> VMobject:
+        return self.submobjects[key]
+


This method is used to define the return type when indexing into a VGroup. If the super class was used, this would return a Mobject, but in a VGroup it should be a VMobject.

henrikmidtiby · 2025-08-10T20:05:06Z

manim/scene/vector_space_scene.py

+        temp = self.get_basis_vectors()
+        i_hat = temp.submobjects[0]
+        j_hat = temp.submobjects[1]


Apparently the trick for defining the type of elements in a VGroup to be VMobject's does not work here. Which is the reason for this workaround.

henrikmidtiby · 2025-08-10T20:06:02Z

manim/scene/vector_space_scene.py

+        temp = array.get_entries()
+        x_coord = temp.submobjects[0]
+        y_coord = temp.submobjects[1]


Apparently the trick for defining the type of elements in a VGroup to be VMobject's does not work here. Which is the reason for this workaround.

henrikmidtiby · 2025-08-10T20:06:45Z

manim/utils/color/core.py

@@ -1409,7 +1409,7 @@ def invert_color(color: ManimColorT) -> ManimColorT:
 def color_gradient(
    reference_colors: Sequence[ParsableManimColor],
    length_of_output: int,
-) -> list[ManimColor] | ManimColor:
+) -> list[ManimColor]:


Same change as in PR #4380

henrikmidtiby · 2025-08-10T20:07:00Z

manim/utils/color/core.py

@@ -1426,7 +1426,7 @@ def color_gradient(
        A :class:`ManimColor` or a list of interpolated :class:`ManimColor`'s.
    """
    if length_of_output == 0:
-        return ManimColor(reference_colors[0])
+        return [ManimColor(reference_colors[0])]


Same change as in PR #4380.

henrikmidtiby · 2025-08-10T20:11:09Z

manim/mobject/mobject.py

+    animation_overrides: dict[
+        type[Animation],
+        FunctionOverride,
+    ] = {}


By specifying the type of animation_overrides here, a lot of type errors like "type[Mobject]" has no attribute "animation_overrides" are removed.

# Conflicts: # manim/mobject/mobject.py

manim/mobject/mobject.py

@@ -1227,7 +1244,7 @@

        return self

-    def scale(self, scale_factor: float, **kwargs) -> Self:
+    def scale(self, scale_factor: float, **kwargs: Any) -> Self:


…in elements during runtime and not only during type checking

henrikmidtiby · 2025-08-11T12:24:35Z

One of the main contributions in this PR is that when accessing elements in a VGroup, the type of these elements are now recognized as VMobjects.

This is achieved by adding/modifying these methods including type annotations to the VMobject class.

def __iter__(self) -> Iterator[VMobject]:
    return iter(self.split())
def split(self) -> list[VMobject]:
    result: list[VMobject] = [self] if len(self.points) > 0 else []
    return result + self.submobjects

And these to the VGroup class.

def __getitem__(self, key: int) -> VMobject:
    return self.submobjects[key]

# Conflicts: # manim/utils/color/core.py

Replace self.lines with self.lines_chars and self.lines_alignment.

# Conflicts: # manim/utils/deprecation.py

for more information, see https://pre-commit.ci

henrikmidtiby added 7 commits August 5, 2025 10:29

Add type annotations to mobject.py

af65634

More work on type annotations for mobject.py

8df3447

...

b502836

Merge branch 'main' into TypingMobject

72deed5

Almost handled all mypy errors

07e1074

Add the mypy error messages to the lines that trigger them

4af521c

Use typing.cast to avoid some mypy errors, as suggested by JasonGrace…

7183ad1

…2282

github-project-automation bot added this to Dev Board Aug 10, 2025

github-project-automation bot moved this to 🆕 New in Dev Board Aug 10, 2025

henrikmidtiby added 5 commits August 10, 2025 21:23

Used the ruff linter

d0e603e

Fixed one typing issue and added the error descriptions to the source…

acc2ff8

… code for the remaning 10 errors

Set the type of the elements in a VGroup to VMobject

01f33a0

Use typing.cast to handle some specific cases.

baf7e3d

Code cleaning

6dbfcf8

henrikmidtiby commented Aug 10, 2025

View reviewed changes

Updates

62513fd

henrikmidtiby commented Aug 10, 2025

View reviewed changes

Merge remote-tracking branch 'upstream/main' into TypingMobject

37aaa7f

# Conflicts: # manim/mobject/mobject.py

github-advanced-security bot found potential problems Aug 10, 2025

View reviewed changes

henrikmidtiby added 5 commits August 11, 2025 07:56

When started to use typing.cast it is needed to import / define certa…

107fbe2

…in elements during runtime and not only during type checking

Fix bug introduced with the type annotations.

3a2f3b5

Made it work again

c75fbdc

..

34ecaf7

Fixed more issues.

17ca755

henrikmidtiby added 4 commits August 11, 2025 14:39

Code cleanup

061e033

Merge remote-tracking branch 'upstream/main' into TypingMobject

618c885

# Conflicts: # manim/utils/color/core.py

Code cleanup.

84bdfe2

Replace self.lines with self.lines_chars and self.lines_alignment.

Handle slicing when accessing elements inside a VGroup

a17bb30

henrikmidtiby changed the title ~~Typing mobject.py~~ Add type annotations to mobject.py Aug 13, 2025

henrikmidtiby mentioned this pull request Aug 13, 2025

Typing progress tracker #3375

Open

22 tasks

RBerga06 mentioned this pull request Aug 15, 2025

Add type annotations to opengl_mobject.py #4398

Merged

3 tasks

henrikmidtiby and others added 8 commits August 21, 2025 22:55

Merge remote-tracking branch 'upstream/main' into TypingMobject

776865e

Fix missing issues.

e2eaccf

Merge remote-tracking branch 'upstream/main' into TypingMobject

be92b75

# Conflicts: # manim/utils/deprecation.py

Silence the last mypy error

8202a40

Make _Updater, _NonTimeBasedUpdater and _TimeBasedUpdater private.

3e2a161

Replace | with Union[...] in one location

63ed382

Move import of Union

a3fe7e4

[pre-commit.ci] auto fixes from pre-commit.com hooks

15d4832

for more information, see https://pre-commit.ci

henrikmidtiby marked this pull request as ready for review August 21, 2025 21:31

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		def __getitem__(self, key: int) -> VMobject:
		return self.submobjects[key]

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Overview: What does this pull request change?

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Add type annotations to `mobject.py` #4388

Add type annotations to `mobject.py` #4388

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