Fix emperor_dilemma: relative imports and outdated SpaceRenderer API

[mehaksalil]

The emperor_dilemma example is currently broken and cannot be run due to two issues:

1. Relative imports in app.py, model.py, and agents.py are incompatible with
   how Solara loads example modules.

2. SpaceRenderer.setup_agents() no longer exists in the current Mesa API.

Both issues prevent the example from running at all.

[codebreaker32]

1. Relative imports in app.py, model.py, and agents.py are incompatible with
   how Solara loads example modules.

As far as I know, it is working fine.

2. SpaceRenderer.setup_agents() no longer exists in the current Mesa API.

It exists in the current API.

Both issues prevent the example from running at all.

Any MRE to support your argument?

[mehaksalil]

Here's a screenshot of the error on a fresh clone following the README instructions exactly. The relative import fails when running solara run app.py from inside the emperor_dilemma directory as the README instructs. This is reproducible and not environment-specific.
I understand the tests are failing with my fix, I'm working on a solution that satisfies both Solara's module loading and the CI test runner. Happy to collaborate on the right approach if you have a preferred solution in mind.

[mehaksalil]

When i fix those imports, (by using absolute imports) this was the next error i found:

I ran the example, according to the README provided. Please let me know if I'm not supposed to be facing this error and right way to run the example

[codebreaker32]

Please share complete trace stack

[mehaksalil]

ERROR: Traceback (most recent call last):
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\starlette\routing.py", line 694, in lifespan
async with self.lifespan_context(app) as maybe_state:
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\starlette\routing.py", line 571, in aenter
await self._router.startup()
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\starlette\routing.py", line 673, in startup
handler()
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\server\starlette.py", line 620, in on_startup
appmod.ensure_apps_initialized()
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\util.py", line 345, in wrapper
return_value = f()
^^^
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\server\app.py", line 542, in ensure_apps_initialized
app.init()
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\server\app.py", line 106, in init
app = self._execute()
^^^^^^^^^^^^^^^
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\server\app.py", line 153, in _execute
routes = [solara.autorouting._generate_route_path(self.path, first=True, initial_namespace=initial_namespace)]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\autorouting.py", line 525, in _generate_route_path
module = source_to_module(subpath, initial_namespace=initial_namespace)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\autorouting.py", line 39, in source_to_module
exec(ast, mod.dict)
File "C:\Users\mehak\mesa\mesa-examples\examples\emperor_dilemma\app.py", line 10, in
from .model import EmperorModel
ImportError: attempted relative import with no known parent package

ERROR: Application startup failed. Exiting.

[mehaksalil]

second error faced:

ERROR: Traceback (most recent call last):
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\starlette\routing.py", line 694, in lifespan
async with self.lifespan_context(app) as maybe_state:
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\starlette\routing.py", line 571, in aenter
await self._router.startup()
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\starlette\routing.py", line 673, in startup
handler()
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\server\starlette.py", line 620, in on_startup
appmod.ensure_apps_initialized()
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\util.py", line 345, in wrapper
return_value = f()
^^^
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\server\app.py", line 542, in ensure_apps_initialized
app.init()
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\server\app.py", line 106, in init
app = self._execute()
^^^^^^^^^^^^^^^
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solara\server\app.py", line 153, in _execute
routes = [solara.autorouting._generate_route_path(self.path, first=True, initial_namespace=initial_namespace)]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\mehak\AppData\Local\Programs\Python\Python311\Lib\site-packages\solae-packages\solara\autorouting.py", line 39, in source_to_module
exec(ast, mod.dict)
File "C:\Users\mehak\mesa\mesa-examples\examples\emperor_dilemma\app.py", line 91, in
).setup_agents(emperor_portrayal)
^^^^^^^^^^^^
AttributeError: 'SpaceRenderer' object has no attribute 'setup_agents'

ERROR: Application startup failed. Exiting.

[codebreaker32]

I checked it locally and relative import issue is genuine So I'd suggest moving agents.py and model.py to a separate subpackage in emperor_dilemma directory similar to how other examples are doing

I still couldn't reproduce the second issue

[mehaksalil]

For the second issue, SpaceRenderer.setup_agents() doesn't exist in the current Mesa release. This may be a version difference. Could you share which Mesa version you're running? On the latest release the correct pattern is .render(agent_portrayal=...) as used in examples like rumormill.

[codebreaker32]

Could you share which Mesa version you're running? On the latest release the correct pattern is .render(agent_portrayal=...) as used in examples like rumormill.

You are mistaken. See

https://github.com/mesa/mesa/blob/2cf3a6334988ab9d364e98d3ffd4108d8c63176d/mesa/visualization/space_renderer.py#L164

https://github.com/mesa/mesa/blob/2cf3a6334988ab9d364e98d3ffd4108d8c63176d/mesa/visualization/space_renderer.py#L359

[mehaksalil]

That makes sense, I was on Python 3.11 with Mesa 3.3.1 which doesn't have setup_agents. I'll upgrade to Python 3.12 and retest. I'll drop the SpaceRenderer fix from the PR and focus only on the relative import restructure as you suggested.