VGroup and VDict must override __repr__ to display the mobjects contained

Consider this example:

class Test(Scene):
    def construct(self):
        sq = Square()
        cir = Circle()
        grp = VGroup(sq, cir)
        print(grp) # --> Just prints: VGroup
        self.play(ShowCreation(grp))
        dct = VDict({'s' : sq, 'c' : cir}).next_to(grp, DOWN)
        print(dct) # --> Just prints: VDict
        self.play(ShowCreation(dct))

When there are a lot of mobjects in the VGroup or VDict, it sometimes helps to know what are those mobjects while debugging. Something like [Square, Circle] or even better the full hash name (IDK what it’s called) – manim.mobject....at 0x00.... Let me know how can this be best incorporated.

[huguesdevimeux]

I don’t know the proper name either lol, but the hex thing at the end is the id, I think. And I think the id in the repr can be sometimes useful, when one wants to check if two objects are different.

[behackl]

I would prefer implementing __repr__ over __str__ (see https://stackoverflow.com/questions/1436703/difference-between-str-and-repr), and would love to see more manim classes having proper __repr__ methods. (Note in particular: if __repr__ is defined and __str__ is not, str(object) will still work.)

For the container, I fully agree that its repr should print a list of its children. But for something concrete like Square I would find it useful to let Square(side_length=5) print something like 'Square with side length 5', or even 'Square with side length 5 and center (0., 0., 0.)'; the more explicit and defining the better. (For your PR it is fine to just take care of VGroup and VDict, improving their representation strings is definitely more important. 👍)