Python PySide2中QScxmlStateMachine.connectToEvent的奇怪行为

我正在尝试编写一个桌面应用程序，在后端使用Python，在前端使用QML，并使用scxml创建状态机。我正在使用PySide2。我的意图是通过状态机描述应用程序的逻辑。根据状态，QML中的UI应该做出相应的反应。此外，后端应根据输入的状态等执行方法

我的项目由3个文件组成：

main.py

带有后端逻辑，

ui.qml

带有ui，

stateMachine.scxml

带有状态机

main.py的内容

：

from PySide2.QtScxml import QScxmlStateMachine
from PySide2.QtWidgets import QApplication
from PySide2.QtCore import QUrl, QObject, Slot
from PySide2.QtQml import QQmlApplicationEngine


class BackEnd(QObject):
    def __init__(self):
        super().__init__()

    @Slot()
    def ev_slot(self):
        '''method called on event t1'''
        print('event t1')

    @Slot(bool)
    def st_slot(self, active):
        '''method called on entering and exiting state s2'''
        if active:
            print('s2 entered')
        else:
            print('s2 exited')


app = QApplication([])
qml_url = QUrl("ui.qml")

engine = QQmlApplicationEngine()

# loading state machine
my_state_machine = QScxmlStateMachine.fromFile('stateMachine.scxml')

backend = BackEnd()

# registering state machine in QML context
engine.rootContext().setContextProperty("stateMachine", my_state_machine)
# connecting event of state machine to method of backend
conn1 = my_state_machine.connectToEvent("t1", backend, "aev_slot()")
# connecting state of state machine to method of backend
conn2 = my_state_machine.connectToState("s2", backend, "ast_slot(bool)")

my_state_machine.start()

engine.load(qml_url)

app.exec_()

UI非常简单：它只包含3个按钮，用于向状态机提交事件（

UI.qml

file）：

状态机

stateMachine.scxml

由3种状态组成：

s1

，

s2

，

s3

和转换

t1

，

t2

，

t3

：

<?xml version="1.0" encoding="UTF-8"?>
<scxml xmlns="http://www.w3.org/2005/07/scxml" version="1.0" binding="early" xmlns:qt="http://www.qt.io/2015/02/scxml-ext" name="stateMachine" initial="s1">
    <state id="s1">
        <transition type="external" event="t1" target="s2"/>
        <onentry>
            <log label="entered" expr="s1"/>
        </onentry>
    </state>
    <state id="s2">
        <transition type="external" event="t2" target="s3"/>
        <onentry>
            <log label="entered" expr="s2"/>
        </onentry>
    </state>
    <state id="s3">
        <transition type="external" event="t3" target="s1">
        </transition>
        <onentry>
            <log label="entered" expr="s3"/>
        </onentry>
    </state>
</scxml>

不知何故，方法名称中的第一个字母被忽略了。我做错什么了吗？我对Qt和PySide2非常陌生。总体而言，这是一个好方法吗？我使用的是PySide2 5.11.1a1.dev1530708810518

您必须使用

SLOT（）

将方法作为字符串传递（请记住

SLOT

与

SLOT

装饰器不同）

---

SLOT

仅在SLOT的名称前加前缀

1

，而SIGNAL对

2

也会加前缀，因此如果不想使用它，只需加前缀1:

（…，后端，“1ev_SLOT（）”

，（我不建议这样做，因为它会降低代码的可读性）

<?xml version="1.0" encoding="UTF-8"?>
<scxml xmlns="http://www.w3.org/2005/07/scxml" version="1.0" binding="early" xmlns:qt="http://www.qt.io/2015/02/scxml-ext" name="stateMachine" initial="s1">
    <state id="s1">
        <transition type="external" event="t1" target="s2"/>
        <onentry>
            <log label="entered" expr="s1"/>
        </onentry>
    </state>
    <state id="s2">
        <transition type="external" event="t2" target="s3"/>
        <onentry>
            <log label="entered" expr="s2"/>
        </onentry>
    </state>
    <state id="s3">
        <transition type="external" event="t3" target="s1">
        </transition>
        <onentry>
            <log label="entered" expr="s3"/>
        </onentry>
    </state>
</scxml>

QObject::connect: No such slot BackEnd::v_slot()

from PySide2 import QtCore, QtGui, QtQml, QtScxml


class BackEnd(QtCore.QObject):
    @QtCore.Slot()
    def ev_slot(self):
        '''method called on event t1'''
        print('event t1')

    @QtCore.Slot(bool)
    def st_slot(self, active):
        '''method called on entering and exiting state s2'''
        if active:
            print('s2 entered')
        else:
            print('s2 exited')


if __name__ == '__main__':
    import sys
    app = QtGui.QGuiApplication(sys.argv)
    qml_url = QtCore.QUrl.fromLocalFile("ui.qml")

    # loading state machine
    my_state_machine = QtScxml.QScxmlStateMachine.fromFile('stateMachine.scxml')

    backend = BackEnd()
    conn1 = my_state_machine.connectToEvent("t1", backend, QtCore.SLOT("ev_slot()"))
    conn2 = my_state_machine.connectToState("s2", backend, QtCore.SLOT("st_slot(bool)"))
    my_state_machine.start()

    engine = QtQml.QQmlApplicationEngine()
    engine.rootContext().setContextProperty("stateMachine", my_state_machine)
    engine.load(qml_url)

    if not engine.rootObjects():
        sys.exit(-1)

    sys.exit(app.exec_())