fsm package

Submodules

fsm module

class fsm.InvalidTransition

Bases: exceptions.Exception

Moving from an state to another is not possible.

class fsm.FiniteStateMachineMixin

Bases: fsm.fsm.BaseFiniteStateMachineMixin

A drop in implementation. Ready to be used.

Replace FIELD_NAME in order to automatically retrieve or set from a different field.

In order to use with django, just add a field state or as defined in FIELD_NAME and remember to use change_state instead of simply assigning it

FIELD_NAME = 'state'

current_state()

set_state(state)

class fsm.BaseFiniteStateMachineMixin

Base Mixin to add a state_machine behavior.

Represents the state machine for the object.

The states and transitions should be specified in the following way:

state_machine = {
   'some_state': '__all__'
   'another_state': ('some_state', 'one_more_state')
   'one_more_state': None
}

Requires the implementation of current_state and set_state

can_change(next_state)

Validates if the next_state can be executed or not.

It uses the state_machine attribute in the class.

change_state(next_state, **kwargs)

Performs a transition from current state to the given next state if possible.

Callbacks will be exacuted before an after changing the state. Specific state callbacks will also be called if they are implemented in the subclass.

Parameters:next_state (str or int) – where the state must go Returns:new state. Return type:str or int Raises:InvalidTransition – If transitioning is not possible

current_state()

Returns the current state in the FSM.

get_valid_transitions()

Return possible states to whom a product can transition.

Returns:valid transitions Return type:tuple or list

on_before_change_state(previous_state, next_state, **kwargs)

Called before a state changes.

Parameters:

• previous_state (str or int) – type depends on the definition of the states.
• next_state (str or int) – type depends on the definition of the states.

on_change_state(previous_state, next_state, **kwargs)

Called after a state changes.

Parameters:

• previous_state (str or int) – type depends on the definition of the states.
• next_state (str or int) – type depends on the definition of the states.

set_state(state)

Update the internal state field.

Parameters:state (str or int) – type depends on the definition of the states.

state_machine = None

Module contents

Initializing package.