hammurabi.preconditions package

Submodules

hammurabi.preconditions.base module

This module contains the definition of Preconditions which describes what to do with the received parameter and does the necessary changes. The preconditions are used to enable developers skipping or enabling rules based on a set of conditions.

Warning

The precondition is for checking that a rule should or shouldn’t run, not for breaking/aborting the execution. To indicate a precondition failure as an error in the logs, create a precondition which raises an exception if the requirements doesn’t match.

class hammurabi.preconditions.base.Precondition(name: Optional[str] = None, param: Optional[Any] = None)[source]

Bases: hammurabi.rules.abstract.AbstractRule, abc.ABC

This class which describes the bare minimum and helper functions for Preconditions. A precondition defines what and how should be checked/validated before executing a Rule. Since preconditions are special rules, all the functions available what can be used for hammurabi.rules.base.AbstractRule.

As said, preconditions are special from different angles. While this is not true for Rules, Preconditions will always have a name, hence giving a name to a Precondition is not necessary. In case no name given to a precondition, the name will be the name of the class and ” precondition” suffix.

Example usage:

>>> import logging
>>> from typing import Optional
>>> from pathlib import Path
>>> from hammurabi import Precondition
>>>
>>> class IsFileExists(Precondition):
>>>     def __init__(self, path: Optional[Path] = None, **kwargs):
>>>         super().__init__(None, path, **kwargs)
>>>
>>>     def task(self) -> bool:
>>>         return self.param and self.param.exists()
Parameters

  • name (Optional[str]) – Name of the rule which will be used for printing

  • param (Any) – Input parameter of the rule will be used as self.param

execute() → bool[source]

Execute the precondition.

Raise

AssertionError

Returns

None

made_changes
name
param
abstract task() → bool[source]

Abstract method representing how a hammurabi.rules.base.Precondition.task() must be parameterized. Any difference in the parameters or return type will result in pylint/mypy errors.

To be able to use the power of pipe and children, return something which can be generally used for other rules as in input.

Returns

Returns an output which can be used as an input for other rules

Return type

Any (usually same as self.param’s type)

Module contents