PySide6.QtStateMachine.QHistoryState

class QHistoryState

The QHistoryState class provides a means of returning to a previously active substate. More…

Inheritance diagram of PySide6.QtStateMachine.QHistoryState

Synopsis

Properties

Methods

Signals

Note

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Detailed Description

A history state is a pseudo-state that represents the child state that the parent state was in the last time the parent state was exited. A transition with a history state as its target is in fact a transition to one or more other child states of the parent state. QHistoryState is part of Qt State Machine Framework .

Use the setDefaultState() function to set the state that should be entered if the parent state has never been entered. Example:

machine = QStateMachine()

s1 = QState()
s11 = QState(s1)
s12 = QState(s1)

s1h = QHistoryState(s1)
s1h.setDefaultState(s11)

machine.addState(s1)

s2 = QState()
machine.addState(s2)

button = QPushButton()
# Clicking the button will cause the state machine to enter the child state
# that s1 was in the last time s1 was exited, or the history state's default
# state if s1 has never been entered.
s1.addTransition(button.clicked, s1h)

If more than one default state has to be entered, or if the transition to the default state(s) has to be acted upon, the defaultTransition should be set instead. Note that the eventTest() method of that transition will never be called: the selection and execution of the transition is done automatically when entering the history state.

By default a history state is shallow, meaning that it won’t remember nested states. This can be configured through the historyType property.

class HistoryType

This enum specifies the type of history that a QHistoryState records.

Constant

Description

QHistoryState.ShallowHistory

Only the immediate child states of the parent state are recorded. In this case a transition with the history state as its target will end up in the immediate child state that the parent was in the last time it was exited. This is the default.

QHistoryState.DeepHistory

Nested states are recorded. In this case a transition with the history state as its target will end up in the most deeply nested descendant state the parent was in the last time it was exited.

Note

Properties can be used directly when from __feature__ import true_property is used or via accessor functions otherwise.

property defaultStateᅟ: QAbstractState

This property holds the default state of this history state.

Access functions:
property defaultTransitionᅟ: QAbstractTransition

This property holds the default transition of this history state.

Access functions:
property historyTypeᅟ: QHistoryState.HistoryType

This property holds the type of history that this history state records.

The default value of this property is ShallowHistory .

Access functions:
__init__([parent=None])
Parameters:

parent – QState

Constructs a new shallow history state with the given parent state.

__init__(type[, parent=None])
Parameters:

Constructs a new history state of the given type, with the given parent state.

defaultState()
Return type:

QAbstractState

Returns this history state’s default state. The default state indicates the state to transition to if the parent state has never been entered before.

Getter of property defaultStateᅟ .

defaultStateChanged()

This signal is emitted when the defaultState property is changed.

See also

defaultState

Notification signal of property defaultStateᅟ .

defaultTransition()
Return type:

QAbstractTransition

Returns this history state’s default transition. The default transition is taken when the history state has never been entered before. The target states of the default transition therefore make up the default state.

Getter of property defaultTransitionᅟ .

defaultTransitionChanged()

This signal is emitted when the defaultTransition property is changed.

Notification signal of property defaultTransitionᅟ .

historyType()
Return type:

HistoryType

Returns the type of history that this history state records.

See also

setHistoryType()

Getter of property historyTypeᅟ .

historyTypeChanged()

This signal is emitted when the historyType property is changed.

See also

historyType

Notification signal of property historyTypeᅟ .

setDefaultState(state)
Parameters:

state – QAbstractState

Sets this history state’s default state to be the given state. state must be a sibling of this history state.

Note that this function does not set state as the initial state of its parent.

See also

defaultState()

Setter of property defaultStateᅟ .

setDefaultTransition(transition)
Parameters:

transition – QAbstractTransition

Sets this history state’s default transition to be the given transition. This will set the source state of the transition to the history state.

Note that the eventTest method of the transition will never be called.

Setter of property defaultTransitionᅟ .

setHistoryType(type)
Parameters:

type – HistoryType

Sets the type of history that this history state records.

See also

historyType()

Setter of property historyTypeᅟ .