QState

The QState class provides a general-purpose state for QStateMachine . More…

Inheritance diagram of PySide2.QtCore.QState

Inherited by: QStateMachine

New in version 4.6.

Synopsis

Functions

Detailed Description

QState objects can have child states, and can have transitions to other states. QState is part of The State Machine Framework .

The addTransition() function adds a transition. The removeTransition() function removes a transition. The transitions() function returns the state’s outgoing transitions.

The assignProperty() function is used for defining property assignments that should be performed when a state is entered.

Top-level states must be passed a QStateMachine object as their parent state, or added to a state machine using addState() .

States with Child States

The childMode property determines how child states are treated. For non-parallel state groups, the setInitialState() function must be called to set the initial state. The child states are mutually exclusive states, and the state machine needs to know which child state to enter when the parent state is the target of a transition.

The state emits the finished() signal when a final child state ( QFinalState ) is entered.

The setErrorState() sets the state’s error state. The error state is the state that the state machine will transition to if an error is detected when attempting to enter the state (e.g. because no initial state has been set).

class QState([parent=None])

QState(childMode[, parent=None])

param parent

QState

param childMode

ChildMode

Constructs a new state with the given parent state.

Constructs a new state with the given childMode and the given parent state.

PySide2.QtCore.QState.ChildMode

This enum specifies how a state’s child states are treated.

Constant

Description

QState.ExclusiveStates

The child states are mutually exclusive and an initial state must be set by calling setInitialState() .

QState.ParallelStates

The child states are parallel. When the parent state is entered, all its child states are entered in parallel.
PySide2.QtCore.QState.RestorePolicy

This enum specifies the restore policy type. The restore policy takes effect when the machine enters a state which sets one or more properties. If the restore policy is set to , the state machine will save the original value of the property before the new value is set.

Later, when the machine either enters a state which does not set a value for the given property, the property will automatically be restored to its initial value.

Only one initial value will be saved for any given property. If a value for a property has already been saved by the state machine, it will not be overwritten until the property has been successfully restored.

Constant

Description

QState.DontRestoreProperties

The state machine should not save the initial values of properties and restore them later.

QState.RestoreProperties

The state machine should save the initial values of properties and restore them later.

See also

globalRestorePolicy assignProperty()

PySide2.QtCore.QState.addTransition(arg__1, arg__2)
Parameters
Return type

QSignalTransition

PySide2.QtCore.QState.addTransition(target)
Parameters

target – QAbstractState

Return type

QAbstractTransition

Adds an unconditional transition from this state to the given target state, and returns then new transition object.

PySide2.QtCore.QState.addTransition(transition)
Parameters

transition – QAbstractTransition

Adds the given transition . The transition has this state as the source. This state takes ownership of the transition.

PySide2.QtCore.QState.addTransition(sender, signal, target)
Parameters
Return type

QSignalTransition

Adds a transition associated with the given signal of the given sender object, and returns the new QSignalTransition object. The transition has this state as the source, and the given target as the target state.

PySide2.QtCore.QState.assignProperty(object, name, value)
Parameters

  • object – QObject

  • name – str

  • value – object

Instructs this state to set the property with the given name of the given object to the given value when the state is entered.

See also

propertiesAssigned()

PySide2.QtCore.QState.childMode()
Return type

ChildMode

Returns the child mode of this state.

See also

setChildMode()

PySide2.QtCore.QState.errorState()
Return type

QAbstractState

Returns this state’s error state.

See also

setErrorState() error()

PySide2.QtCore.QState.initialState()
Return type

QAbstractState

Returns this state’s initial state, or 0 if the state has no initial state.

See also

setInitialState()

PySide2.QtCore.QState.removeTransition(transition)
Parameters

transition – QAbstractTransition

Removes the given transition from this state. The state releases ownership of the transition.

See also

addTransition()

PySide2.QtCore.QState.setChildMode(mode)
Parameters

mode – ChildMode

Sets the child mode of this state.

See also

childMode()

PySide2.QtCore.QState.setErrorState(state)
Parameters

state – QAbstractState

Sets this state’s error state to be the given state . If the error state is not set, or if it is set to 0, the state will inherit its parent’s error state recursively. If no error state is set for the state itself or any of its ancestors, an error will cause the machine to stop executing and an error will be printed to the console.

See also

errorState()

PySide2.QtCore.QState.setInitialState(state)
Parameters

state – QAbstractState

Sets this state’s initial state to be the given state . state has to be a child of this state.

See also

initialState()

PySide2.QtCore.QState.transitions()
Return type

Returns this state’s outgoing transitions (i.e. transitions where this state is the source state ), or an empty list if this state has no outgoing transitions.

See also

addTransition()