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# QState Class Reference
[QtCore module]

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

Inherits QAbstractState.

Inherited by QStateMachine.

### Types

- enum ChildMode { ExclusiveStates, ParallelStates }

### Methods

- __init__ (self, QState parent = None)
- __init__ (self, ChildMode childMode, QState parent = None)
- addTransition (self, QAbstractTransition transition)
- QSignalTransition addTransition (self, QObject sender, object signal, QAbstractState target)
- QSignalTransition addTransition (self, object signal, QAbstractState target)
- QAbstractTransition addTransition (self, QAbstractState target)
- assignProperty (self, QObject object, str name, QVariant value)
- ChildMode childMode (self)
- QAbstractState errorState (self)
- bool event (self, QEvent e)
- QAbstractState initialState (self)
- onEntry (self, QEvent event)
- onExit (self, QEvent event)
- removeTransition (self, QAbstractTransition transition)
- setChildMode (self, ChildMode mode)
- setErrorState (self, QAbstractState state)
- setInitialState (self, QAbstractState state)
- unknown-type transitions (self)

### Qt Signals

- void finished ()
- void propertiesAssigned ()

## Detailed Description

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

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 QStateMachine.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 QState.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).

## Type Documentation

### QState.ChildMode

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

Constant | Value | Description
--- | --- | ---
`QState.ExclusiveStates` | `0` | The child states are mutually exclusive and an initial state must be set by calling QState.setInitialState().
`QState.ParallelStates` | `1` | The child states are parallel. When the parent state is entered, all its child states are entered in parallel.

## Method Documentation

### QState.__init__ (self, QState parent = None)

The parent argument, if not None, causes self to be owned by Qt instead of PyQt.

Constructs a new state with the given parent state.

### QState.__init__ (self, ChildMode childMode, QState parent = None)

The parent argument, if not None, causes self to be owned by Qt instead of PyQt.

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

### QState.addTransition (self, QAbstractTransition transition)

The transition argument has it's ownership transferred to Qt.

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

### QSignalTransition QState.addTransition (self, QObject sender, object signal, QAbstractState target)

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.

### QSignalTransition QState.addTransition (self, object signal, QAbstractState target)

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

### QAbstractTransition QState.addTransition (self, QAbstractState target)

The target argument has it's ownership transferred to Qt.

### QState.assignProperty (self, QObject object, str name, QVariant value)

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().

### ChildMode QState.childMode (self)

### QAbstractState QState.errorState (self)

### bool QState.event (self, QEvent e)

Reimplemented from QObject.event().

### QAbstractState QState.initialState (self)

### QState.onEntry (self, QEvent event)

Reimplemented from QAbstractState.onEntry().

### QState.onExit (self, QEvent event)

Reimplemented from QAbstractState.onExit().

### QState.removeTransition (self, QAbstractTransition transition)

The transition argument

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

See also addTransition().

### QState.setChildMode (self, ChildMode mode)

### QState.setErrorState (self, QAbstractState state)

### QState.setInitialState (self, QAbstractState state)

### unknown-type QState.transitions (self)

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.

This function was introduced in Qt 4.7.

See also addTransition().

## Qt Signal Documentation

### void finished ()

This is the default overload of this signal.

This signal is emitted when a final child state of this state is entered.

See also QFinalState.

### void propertiesAssigned ()

This is the default overload of this signal.

This signal is emitted when all properties have been assigned their final value. If the state assigns a value to one or more properties for which an animation exists (either set on the transition or as a default animation on the state machine), then the signal will not be emitted until all such animations have finished playing.

If there are no relevant animations, or no property assignments defined for the state, then the signal will be emitted immediately before the state is entered.

See also QState.assignProperty() and QAbstractTransition.addAnimation().