genstates 0.1.2

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GenStates

GenStates is an implentation of state machine, with genruler as the rule engine.

Usage

from genstates import Machine
import yaml

with open('schema.yaml') as file_schema:
    machine = Machine(yaml.safe_load(file_schema))

Fetching states

• Get initial state by machine.initial
• Get any state by machine.states[$key] where $key is the key for the state

Fetching transitions

• Get all possible transitions for a given state by

  transitions = machine.get_transitions(state)
  

• Get a specific transition for a given state by

  transition = machine.get_transition(state, transition_key)
  

Progressing from one state to another

• If you have a known transition, pass in a context dictionary that the rule understands

  transition.check_condition(context)
  

• If you are not sure about the destination, use .progress()

  destination_state = machine.progress(current_state, context)
  

  Note that if multiple transitions are possible it will result in an error

Schema

Assuming you are storing the transition as a YAML

machine:
  initial_state: $initial_state

states:
  $state_key: # can have many states
    name: $state_name
    transitions: # can have many transitions
      $transition_key:
        name: $transition_name
        destination: $transition_destination
        rule: $transition_rule

where:

• $initial_state: a state key value, must be defined in the states section
• $state_key: a unique key for the state
• state_name: a descriptive name for the state
• $transition_key: a unique key for the transition
• $transition_destination: a state key value, must be defined in the states section, pointing back to the same state is allowed
• $transition_name: a descriptive name for the transition
• $transition_rule: a rule that has to return True