Parameters

The Parameters container (spx_core/system/parameters.py) is the simplest way to push constant values into your model when it starts. Think of it as a batch of assignments that run during prepare().

Configuration Example

YAML

parameters:
  attributes.voltage.default: 230.0
  attributes.mode.default: "production"
  instances.controller.parameters.gain: 1.2

JSON

How it works

• Each key is an attribute reference resolved via resolve_attribute_reference_hierarchical.

• The container sets the attribute's internal value by default.

• If the reference points at an external wrapper (#external(...)), the external value is updated instead.

Validation

• The container expects a mapping; any other type raises an error.

• If a reference cannot be resolved, a KeyError is raised with the full component path. This usually means the attribute name changed or the instance was not loaded yet.

Best practices

• Use environment variables for deployment-specific values by combining parameters with templates or SDK tooling: generate YAML where default values read from os.environ before shipping it to the server.

• Keep parameter entries close to the attributes they configure—long dotted paths are harder to maintain.

• Document critical parameters (e.g., safety limits) so QA knows what to tweak when running experiments.