Detect invalid element overrides

[alihamdan]

Fixes #186

[Saelyos]

Hello, I'm not sure of the problem you are trying to solve.

If we look at the example linked in #186, and if we run the following code:

import roseau.load_flow as lf
bus = lf.Bus("bus1", phases="an")
load1 = lf.PowerLoad("load1", bus, powers=[1000])
load2 = lf.PowerLoad("load1", bus, powers=[1000])  # <- oops, forgot to change the ID
en = lf.ElectricalNetwork.from_element(bus)

We get the right error message:

roseau.load_flow.exceptions.RoseauLoadFlowException: Duplicate ID for an load in this network: 'load1'. [bad_load_id]

However the problem could arise if we connect the load later on (I had to add a few elements):

import roseau.load_flow as lf
bus = lf.Bus("bus1", phases="an")
vs = lf.VoltageSource("source", bus, voltages=[10])
pref = lf.PotentialRef("pref", bus)
load1 = lf.PowerLoad("load1", bus, powers=[1000])
en = lf.ElectricalNetwork.from_element(bus)
load2 = lf.PowerLoad("load1", bus, powers=[1000])  # <- oops, forgot to change the ID

In that case no error message is currently raised, but it should be easy to add in the ElectricalNetwork._connect_element method something like:

elif isinstance(element, AbstractLoad):
    if element.id in self.loads:
        raise RoseauLoadFlowException("Duplicate ID...", code=error_code)
    self.loads[element.id] = element

This seems simpler than modifying every elements _connected_elements attributes. What do you think ?

[alihamdan]

However the problem could arise if we connect the load later on

Yes, this is the main problem we are trying to solve.

This seems simpler than modifying every elements _connected_elements attributes. What do you think ?

You are right, and that's why the PR is still a draft 😉.
I started by changing the _connected_elements to a dictionary and adding the check there following the suggeston of Benoît but then realized that this does not detect all cases and we have to modify the network's _connect_element method instead anyway.