from __future__ import annotations
import copy
from openfisca_core.parameters import ParameterNode
from openfisca_core.taxbenefitsystems import TaxBenefitSystem
[docs]
class Reform(TaxBenefitSystem):
"""A modified TaxBenefitSystem.
All reforms must subclass `Reform` and implement a method `apply()`.
In this method, the reform can add or replace variables and call `modify_parameters` to modify the parameters of the legislation.
Example:
>>> from openfisca_core import reforms
>>> from openfisca_core.parameters import load_parameter_file
>>>
>>> def modify_my_parameters(parameters):
>>> # Add new parameters
>>> new_parameters = load_parameter_file(name='reform_name', file_path='path_to_yaml_file.yaml')
>>> parameters.add_child('reform_name', new_parameters)
>>>
>>> # Update a value
>>> parameters.taxes.some_tax.some_param.update(period=some_period, value=1000.0)
>>>
>>> return parameters
>>>
>>> class MyReform(reforms.Reform):
>>> def apply(self):
>>> self.add_variable(some_variable)
>>> self.update_variable(some_other_variable)
>>> self.modify_parameters(modifier_function = modify_my_parameters)
"""
name = None
def __init__(self, baseline) -> None:
""":param baseline: Baseline TaxBenefitSystem."""
super().__init__(baseline.entities)
self.baseline = baseline
self.parameters = baseline.parameters
self._parameters_at_instant_cache = baseline._parameters_at_instant_cache
self.variables = baseline.variables.copy()
self.decomposition_file_path = baseline.decomposition_file_path
self.key = self.__class__.__name__
if not hasattr(self, "apply"):
msg = f"Reform {self.key} must define an `apply` function"
raise Exception(msg)
self.apply()
def __getattr__(self, attribute):
return getattr(self.baseline, attribute)
@property
def full_key(self):
key = self.key
assert (
key is not None
), f"key was not set for reform {self} (name: {self.name!r})"
if self.baseline is not None and hasattr(self.baseline, "key"):
baseline_full_key = self.baseline.full_key
key = f"{baseline_full_key}.{key}"
return key
[docs]
def modify_parameters(self, modifier_function):
"""Make modifications on the parameters of the legislation.
Call this function in `apply()` if the reform asks for legislation parameter modifications.
Args:
modifier_function: A function that takes a :obj:`~parameters.ParameterNode`
and should return an object of the same type.
"""
baseline_parameters = self.baseline.parameters
baseline_parameters_copy = copy.deepcopy(baseline_parameters)
reform_parameters = modifier_function(baseline_parameters_copy)
if not isinstance(reform_parameters, ParameterNode):
raise ValueError(
f"modifier_function {modifier_function.__name__} in module {modifier_function.__module__} must return a ParameterNode",
)
self.parameters = reform_parameters
self._parameters_at_instant_cache = {}
return None