ExponentialClassFamily: registry integration and runtime introspection

[LeonidElkin]

ExponentialClassFamily: registry integration and runtime introspection

Task

Integrate ExponentialClassFamily into the existing families infrastructure and make it detectable at runtime.

Requirements

1. Placement and inheritance

• ExponentialClassFamily must live in the families module.
• It must inherit from ParametricFamily.
• It must satisfy the ParametricFamily interface so that any function that expects a ParametricFamily can also accept an ExponentialClassFamily.

2. Registry integration

• Ensure that instances of ExponentialClassFamily can be created and registered in the existing registry (the same mechanism used for “ordinary” parametric families).
• The registry should not need a separate code-path just for exponential families:
  • registration should use the same API as for regular ParametricFamily instances,
  • but it should be possible to query whether a family is exponential-class.

3. Runtime introspection

Provide a minimal mechanism to distinguish at runtime whether a given family is:

• a “generic” parametric family (ParametricFamily without special exponential structure),
• or an exponential-class family (ExponentialClassFamily).

Possible approaches (choose one and document):

• add a boolean property is_exponential_family on ParametricFamily, overridden to True in ExponentialClassFamily;
• rely on isinstance(family, ExponentialClassFamily) checks;
• or a small registry of exponential families.

The chosen approach should:

• be simple to use in downstream code (e.g. Bayesian utilities),
• avoid breaking existing code that only knows about ParametricFamily.