SpxComponent

Overview

An SpxComponent represents a node in a tree of components. Each node can:

• Hold configuration data (definition)

• Track a parent and any number of named children

• Propagate lifecycle calls (e.g. prepare(), run(),

  destroy()) through its subtree

• Behave like a Python dict for child lookup

Because of its generic design, you can subclass SpxComponent to define

specific simulation models—e.g. electrical devices or control‐system

blocks—that plug into MiL workflows.

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Core Attributes

Attribute	Type	Description
name	str	Unique identifier for this component instance.
parent	Optional[SpxComponent]	Reference to the parent component; None if this is the root.
children	Dict[str, SpxComponent]	Mapping of child names to child component instances.
definition	Any	Configuration data used to populate and initialize this component.
state	SpxComponentState	Current lifecycle state (e.g. INITIALIZED, RUNNING, DESTROYED).
logger	logging.Logger	Preconfigured logger under name spx_sdk.SpxComponent.<name>.

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Child Management

component.add_child(child: SpxComponent)      # Add or replace a named child
component.remove_child(child: SpxComponent)   # Remove a child and clear its parent
component.get_children() -> Dict[str, SpxComponent]
component.get_children_list() -> List[SpxComponent]

• Validation

  • Adding a child to itself raises ValueError.

  • Adding non-SpxComponent raises ValueError.

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Dictionary-Like Interface

SpxComponent implements getitem, setitem, contains, and len, letting you treat it like a dict of its children:

child = component['child_name']      # KeyError if not present
component['new_name'] = child_obj    # ValueError if not SpxComponent
'in_child' in component              # True or False
n = len(component)                   # Number of children
maybe = component.get('child', None) # Safe lookup with default

This makes dynamic tree construction and traversal concise and Pythonic.

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Lifecycle Methods

Each lifecycle call:

1. Logs the action

2. Updates self.state

3. Propagates the call to all children

prepare()	Sets state → PREPARING; children → prepare(); → PREPARED
run()	→ RUNNING; children → run(); → STOPPED
start()	Alias for run().
pause()	→ PAUSING; children → pause(); → PAUSED
stop()	→ STOPPING; children → stop(); → STOPPED
reset()	→ STOPPING; children → reset(); → STOPPED
destroy()	→ DESTROYING; children → destroy(); clears children; → DESTROYED

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Extending for Simulation Models

To create a custom component—e.g. a device block in an MiL setup—subclass

SpxComponent (or Item if you’re using the SPX container pattern):

from spx_sdk.components import SpxComponent, SpxComponentState

class VoltageSource(SpxComponent):
    def _populate(self, definition: dict):
        # Parse parameters: e.g. amplitude, frequency
        super()._populate(definition)
        self.voltage = float(definition.get("voltage", 1.0))
        self.frequency = float(definition.get("frequency", 60.0))

    def prepare(self, *args, **kwargs) -> bool:
        self.logger.debug(f"Configuring {self.name}: {self.voltage}V @ {self.frequency}Hz")
        return super().prepare(*args, **kwargs)

    def run(self, *args, **kwargs) -> bool:
        # Inject into MiL signal bus here...
        self.logger.debug(f"Emitting voltage {self.voltage}V")
        return super().run(*args, **kwargs)

• _populate: Override to extract domain-specific properties from

  definition. Always call super() first.

• Lifecycle hooks: Add logging or custom behavior before/after

  calling super().prepare() / super().run(), etc.

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Usage Examples

Simple Hierarchy

root = SpxComponent(name="root")
child_a = SpxComponent(name="sensor", parent=root)
child_b = SpxComponent(name="controller", parent=root)

print(f"Children of root: {list(root.children.keys())}")  # ["sensor","controller"]
print("sensor" in root)                                   # True
print(len(root))                                          # 2

Integrating in MiL System

# Build a network of simulated devices
config = {
    "voltage_source": {"voltage": 5.0, "frequency": 50.0},
    "load":           {"resistance": 100.0}
}
power_net = SpxComponent(name="PowerNetwork", definition=config)
# power_net now has two children: VoltageSource and LoadDevice (if registered)
power_net.prepare()
power_net.run()

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Best Practices

• Unique Names: Use descriptive, unique name values to avoid collisions.

• Docstrings: Document any overrides of _populate or lifecycle methods.

• Composition: If your model contains distinct sub-elements, nest them as children.

• Logging: Leverage self.logger.debug for traceability in MiL runs.

• Dictionary Interface: Prefer component.get("child") or 'child' in component over manual children[...] access.