State machine model#

class besser.BUML.metamodel.state_machine.state_machine.Body(name: str, callable: Callable)[source]#

Bases: Method

The body of the state of a state machine.

Each state has a Body, which defines the sequence of actions to be executed when an event causes the transition to a state (and a secondary body, i.e., a fallback body, that defines the actions to be executed in case of error in the machine).

Parameters:

name (str) – The name of the body.
callable (Callable) – The function containing the body’s code.

name#

Inherited from Method, represents the name of the body.

Type:: str

visibility#

Inherited from Method, represents the visibility of the body.

Type:: str

type#

Inherited from Method, represents the type of the body.

Type:: Type

is_abstract#

Inherited from Method, indicates if the body is abstract.

Type:: bool

parameters#

Inherited from Method, the set of parameters for the body.

Type:: set[structural.Parameter]

owner#

Inherited from Method, the type that owns the property.

Type:: Type

code#

Inherited from Method, code of the body.

Type:: str

_abc_impl = <_abc._abc_data object>#

class besser.BUML.metamodel.state_machine.state_machine.Condition(name: str, callable: Callable)[source]#

Bases: Method

The representation of a condition (i.e., a boolean function) that may cause the transition of state in a state machine.

Parameters:

name (str) – The name of the condition.
callable (Callable) – The function containing the condition’s code.

name#

Inherited from Method, represents the name of the condition.

Type:: str

visibility#

Inherited from Method, represents the visibility of the condition.

Type:: str

type#

Inherited from Method, represents the type of the condition.

Type:: Type

is_abstract#

Inherited from Method, indicates if the condition is abstract.

Type:: bool

parameters#

Inherited from Method, the set of parameters for the condition.

Type:: set[structural.Parameter]

owner#

Inherited from Method, the type that owns the property.

Type:: Type

code#

Inherited from Method, code of the condition.

Type:: str

_abc_impl = <_abc._abc_data object>#

class besser.BUML.metamodel.state_machine.state_machine.ConfigProperty(section: str, name: str, value: Any)[source]#

Bases: object

A configuration property of a state machine.

Parameters:

section (str) – The section the configuration property belongs to
name (str) – The name of the configuration property
value (Any) – Te value of the configuration property

section#

The section the configuration property belongs to

Type:: str

name#

The name of the configuration property

Type:: str

value#

Te value of the configuration property

Type:: Any

class besser.BUML.metamodel.state_machine.state_machine.Event(name: str)[source]#

Bases: NamedElement

The representation of an event (i.e., external or internal stimuli or input) that may cause the transition of state in a state machine.

Parameters:: name (str) – The name of the event.

name#

Inherited from NamedElement, represents the name of the event.

Type:: str

_abc_impl = <_abc._abc_data object>#

class besser.BUML.metamodel.state_machine.state_machine.Session[source]#

Bases: object

A user session in a state machine execution.

When a user starts interacting with a state machine, a session is assigned to him/her to store user related information, such as the current state or any custom variable. A session can be accessed from the body of the states to read/write user information. If a state machine does not have the concept of ‘users’ (i.e., there are no concurrent executions of the state machine, but a single one) then it could simply have 1 unique session.

id#

The session id, which must unique among all state machine sessions

Type:: str

current_state#

The current state in the state machine for this session

Type:: str

delete(key: str) → None[source]#

Delete an entry of the session private data storage.

Parameters:: key (str) – the entry key

get(key: str) → Any[source]#

Get an entry of the session private data storage.

Parameters:: key (str) – the entry key
Returns:: the entry value, or None if the key does not exist
Return type:: Any

move(transition: Transition) → None[source]#

Move to another state of the state machine.

Parameters:: transition (Transition) – the transition that points to the state to move

set(key: str, value: Any) → None[source]#

Set an entry to the session private data storage.

Parameters:

key (str) – the entry key
value (Any) – the entry value

class besser.BUML.metamodel.state_machine.state_machine.State(sm: StateMachine, name: str, initial: bool = False)[source]#

Bases: NamedElement

A state of a state machine.

Parameters:

sm (StateMachine) – the state machine the state belongs to
name (str) – the state name
initial (bool) – whether the state is initial or not

name#

Inherited from NamedElement, the state name

Type:: str

visibility#

Inherited from NamedElement, determines the kind of visibility of the state (public as default).

Type:: str

sm#

the state machine the state belongs to

Type:: StateMachine

initial#

whether the state is initial or not

Type:: bool

transitions#

The state’s transitions to other states

Type:: list[Transition]

body#

the body of the state

Type:: Body

fallback_body#

the fallback body of the state

Type:: Body

_transition_counter#

Count the number of transitions of this state. Used to name the transitions.

Type:: int

_abc_impl = <_abc._abc_data object>#

_t_name() → str[source]#

Name generator for transitions. Transition names are generic and enumerated. On each call, a new name is generated and the transition counter is incremented for the next name.

Returns:: a name for the next transition
Return type:: str

set_body(body: Body) → None[source]#

Set the state body.

Parameters:: body (Body) – the body

set_fallback_body(body: Body) → None[source]#

Set the state fallback body.

Parameters:: body (Body) – the body

when_condition(condition: Condition) → TransitionBuilder[source]#

when_event(event: Event) → TransitionBuilder[source]#

class besser.BUML.metamodel.state_machine.state_machine.StateMachine(name: str)[source]#

Bases: Model

A state machine model.

Parameters:: name (str) – the state machine name

name#

Inherited from Model, represents the name of the state machine.

Type:: str

visibility#

Inherited from Model, determines the kind of visibility of the state machine (public as default).

Type:: str

states#

the states of the state machine

Type:: list[State]

properties#

the configuration properties of the state machine.

Type:: list[ConfigProperty]

_abc_impl = <_abc._abc_data object>#

add_property(property: ConfigProperty) → ConfigProperty[source]#

Add a configuration property to the state machine.

Parameters:: property (ConfigProperty) – the property to add
Returns:: the configuration property
Return type:: ConfigProperty

initial_state() → State[source]#

Get the state machine’s initial state. It can be None if it has not been set.

Returns:: the initial state of the machine, if exists
Return type:: State or None

new_property(section: str, name: str, value: Any) → ConfigProperty[source]#

Create a new configuration property on the state machine.

Parameters:

section (str) – The section the configuration property belongs to
name (str) – The name of the configuration property
value (Any) – Te value of the configuration property

Returns:

the configuration property

Return type:

ConfigProperty

new_state(name: str, initial: bool = False) → State[source]#

Create a new state in the state machine.

Parameters:

name (str) – the state name. It must be unique in the state machine.
initial (bool) – whether the state is initial or not. A state machine must have 1 initial state.

Returns:

the state

Return type:

State

set_global_fallback_body(body: Body) → None[source]#

Set the global fallback body for all states in the state machine.

Parameters:: body (Body) – The fallback body to be set for all states.

class besser.BUML.metamodel.state_machine.state_machine.Transition(name: str, source: State, dest: State, event: Event, conditions: list[Condition])[source]#

Bases: NamedElement

A state machine transition from one state (source) to another (destination).

A transition is triggered when an event and/or condition/s occurs.

Parameters:

name (str) – Inherited from NamedElement, the transition name
source (State) – the source state of the transition (from where it is triggered)
dest (State) – the destination state of the transition (where the machine moves to)
event (Callable[[Session, dict], bool]) – the event that triggers the transition
conditions (list[Condition]) – the conditions that trigger the transition

name#

Inherited from NamedElement, the transition name

Type:: str

visibility#

Inherited from NamedElement, determines the kind of visibility of the named element (public as default).

Type:: str

source#

The source state of the transition (from where it is triggered)

Type:: State

dest#

The destination state of the transition (where the machine moves to)

Type:: State

event#

The event that triggers the transition

Type:: Event

conditions#

The conditions that trigger the transition

Type:: list[Condition]

_abc_impl = <_abc._abc_data object>#

is_auto() → bool[source]#

Check if the transition is auto (i.e. no event nor condition linked to it).

Returns:: true if the transition is auto, false otherwise
Return type:: bool

class besser.BUML.metamodel.state_machine.state_machine.TransitionBuilder(source: State, event: Event = None, conditions: list[Condition] = None)[source]#

Bases: object

A transition builder.

This class is used to build transitions, allowing for a “fluent api” syntax where consecutive calls can be made on the same object.

Parameters:

source (State) – the source state of the transition
event (Event) – the event linked to the transition (can be None)
conditions (list[Condition]) – the conditions associated to the transition (can be None)

source#

The source state of the transition

Type:: State

event#

The event linked to the transition (can be None)

Type:: Event

condition#

The conditions associated to the transition (can be None)

Type:: list[Condition]

go_to(dest: State) → None[source]#

Set the destination state of the transition.

Completes the transition builder and effectively adds the source state.

Parameters:: dest (State) – the destination state

with_condition(condition: Condition) → TransitionBuilder[source]#