Mypy error in certain formula engine

[matthias-wende-frequenz]

What happened?

When adding a Power object to a formula engine mypy complains with different error messages

Example 1

On checking this following code:

consumer_excess_power_engine = (
    microgrid.producer().power
    + Power.from_watts(-1000)
).build("excess_power")

mypy reports:

error: Incompatible types in assignment (expression has type "Any | None", variable has type "Sample[Any]")  [assignment]
Found 1 error in 1 file (checked 1 source file)

Example 2

On checking this following code:

consumer_excess_power_engine = (
    microgrid.producer().power
    + microgrid.consumer().power
    + Power.from_watts(-1000)
).build("excess_power")

mypy reports:

error: "Sample3Phase[Any]" has no attribute "value"; maybe "value_p1", "value_p2", or "value_p3"?  [attr-defined]
Found 1 error in 1 file (checked 1 source file)

Example 3

On contrast checking this following, having the Power object in the middle code works:

consumer_excess_power_engine = (
    microgrid.producer().power
    + Power.from_watts(-1000)
    + microgrid.consumer().power
).build("excess_power")

Example 4

This code doesn't work.

consumer_excess_power_engine = (
    Power.from_watts(-1000)
    + microgrid.producer().power
).build("excess_power")

find_bug.py:21: error: "Power" has no attribute "build"  [attr-defined]
find_bug.py:23: error: Unsupported operand types for + ("Power" and "FormulaEngine[Power]")  [operator]
Found 2 errors in 1 file (checked 1 source file)

What did you expect instead?

For the examples 1-3 that work mypy shouldn't complain. We may investigate a way to make Example 4 work.

Affected version(s)

v1.x.x

Affected part(s)

Data pipeline (part:data-pipeline)

Extra information

No response

[shsms]

I'm unable to reproduce, and it is hard for me to believe these errors are from these lines, because they don't make sense for the above lines, even if there is a bug. It is likely that these came from somewhere else. If you have a reproducible example, please share.

[matthias-wende-frequenz]

This is the example app that I was using

import asyncio

from datetime import timedelta
from frequenz.sdk import microgrid
from frequenz.sdk.actor import ResamplerConfig
from frequenz.sdk.timeseries import Power

async def run() -> None:
    # This points to the default Frequenz microgrid sandbox
    microgrid_host = "microgrid.sandbox.api.frequenz.io"
    microgrid_port = 62060

    # Initialize the microgrid
    await microgrid.initialize(
        microgrid_host,
        microgrid_port,
        ResamplerConfig(resampling_period=timedelta(seconds=1)),
    )

    # negative means feed-in power due to the negative sign convention
    consumer_excess_power_engine = (
        microgrid.producer().power
        + microgrid.consumer().power
        + Power.from_watts(-1000)
    ).build("excess_power") # (2)!
    cons_excess_power_recv = consumer_excess_power_engine.new_receiver()

    async for cons_excess_power in cons_excess_power_recv:
        cons_excess_power = cons_excess_power.value
        if cons_excess_power is None:
            continue
        print(f"Consumer excess power: {cons_excess_power}")

def main() -> None:
    asyncio.run(run())

if __name__ == "__main__":
    main()

and you where right, the bug is not in the shared lines but when accessing the received value.

find_bug.py:28: error: "Sample3Phase[Any]" has no attribute "value"; maybe "value_p1", "value_p2", or "value_p3"?  [attr-defined]
Found 1 error in 1 file (checked 1 source file)

[daniel-zullo-frequenz]

@matthias-wende-frequenz ~that error might be due to the channels latest upgrade where value has been renamed to message~

See release notes here

Selected

The value property was renamed to message.

edited: nevermind, the code is not using select

[shsms]

Ok, that makes sense. The overrides all seem to have been made for the 3-phase formulas rather than the 1-phase formulas, for which these operations on single constant values are available: https://github.com/frequenz-floss/frequenz-sdk-python/blob/ca89486bdad5bddff960c0b86a4425bb530b6c0a/src/frequenz/sdk/timeseries/formula_engine/_formula_engine.py#L848-L851