Require Mesa models to be initialized with super().__init__()

[EwoutH]

Remove the workaround for when the model super has not been called, and thereby require Mesa models to be initialized with super().__init__().

class MyModel(mesa.Model):
    def __init__(self):
        super().__init__()  # This is now required!

This is needed to correctly add Agents to the model and setup other Mesa model variables.

This warning was present since Mesa 2.2.0 (#1928), so there has been some time to update for existing users.

This PR contains a second commit that names experimental warning in PropertyLayer correctly in space.py.

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
Schelling	small	🔵 +0.7% [+0.3%, +1.1%]	🔵 -0.3% [-0.5%, -0.1%]
Schelling	large	🔵 +1.4% [+0.9%, +1.9%]	🔵 -1.7% [-2.5%, -0.9%]
WolfSheep	small	🔵 +0.0% [-1.3%, +1.2%]	🔵 -0.6% [-0.9%, -0.3%]
WolfSheep	large	🔵 +0.7% [+0.5%, +1.0%]	🔵 -0.3% [-1.1%, +0.5%]
BoidFlockers	small	🔵 +0.4% [-0.2%, +1.0%]	🔵 -1.0% [-1.7%, -0.1%]
BoidFlockers	large	🔵 +1.0% [+0.3%, +1.7%]	🔵 -0.2% [-0.9%, +0.3%]

[rht]

What about try-except then raise error, instead of a warning, for now? I'm not sure if some people do read the release note for such a subtle change in the way they have to do __init__().

[EwoutH]

I don't think it's a bad idea, but with Mesa 3.0 I would like to clean the codebase and remove it altogether.

In the 3.0 release notes we can put a note to first update to the latest Mesa 2.x, which also contains this warning (and it now has been in there for all 2.2.x and 2.3.x releases).

[EwoutH]

Thought about it some more, and I think you're actually right. It's better to throw an useful error than let it crash without any guidance.