Implement line as a list of dict

[EZoni]

This is an implementation of the suggestion made in #12 (comment).

[jlvay]

But the name is written twice then, which is redundant.

Also, why not

line:
  kind: Line
  ...

?

[ax3l]

Discussed: same problem as #12 (comment)

[EZoni]

@ax3l

This (i.e., overloading the model serialization) is the only way I found so far to produce an output like

kind: Line
line:
- drift1:
    kind: Drift
    length: 0.25
- quad1:
    MagneticMultipoleP:
      Bn1: 1.0
    kind: Quadrupole
    length: 1.0
- drift2:
    kind: Drift
    length: 0.5
- quad2:
    MagneticMultipoleP:
      Bn1: -1.0
    kind: Quadrupole
    length: 1.0
- drift3:
    kind: Drift
    length: 0.5

instead of

kind: Line
line:
- drift1:
    kind: Drift
    length: 0.25
    name: drift1
- quad1:
    MagneticMultipoleP:
      Bn1: 1.0
    kind: Quadrupole
    length: 1.0
    name: quad1
- drift2:
    kind: Drift
    length: 0.5
    name: drift2
- quad2:
    MagneticMultipoleP:
      Bn1: -1.0
    kind: Quadrupole
    length: 1.0
    name: quad2
- drift3:
    kind: Drift
    length: 0.5
    name: drift3

with the name attributes printed out as well (hence repeated).

Do you see other ways to obtain this, other than overloading the model serialization?

I guess we would have to do something similar for the deserialization (through @model_validator(mode="before")?), although I have not been able to make that work just yet.

[EZoni]

Note that the custom deserialization is necessary if we expect that this

yaml_data = yaml.dump(line.model_dump(), default_flow_style=False)
loaded_line = Line(**yaml_data)

should lead to line and loaded_line being identical (which we currently assert in the tests and examples).

[ax3l]

Possible alternative posted in #14 that does keep the API user-friendly :)

[ax3l]

Replaced by #14 :)