PySide6中Signal连接出现positional arguments错误问题排查

尝试将部分PyQt5代码迁移至PySide6，原代码适配PyQt5可正常运行，但在PySide6环境下执行报错。

原代码 #

#from PyQt5 import QtCore,QtWidgets
#from PyQt5.QtCore import QT_VERSION_STR, PYQT_VERSION_STR
from PySide6 import QtCore,QtWidgets
from PySide6 import __version__ as PYQT_VERSION_STR
from PySide6.QtCore import __version__ as QT_VERSION_STR


class DynamicTupleSignal(QtCore.QObject):
    signal = QtCore.Signal(tuple)
    #signal = QtCore.pyqtSignal(tuple)
    def connect(self,func):
        self.signal.connect(func)

    def emit(self,data):
        self.signal.emit(data)

class TestDynamicTupleSignal:
    dynsig=DynamicTupleSignal()

    def __init__(self):
        self.dynsig.connect(self.whattheheck)

    def whattheheck(self,data):
        print(data)

if __name__ == "__main__":
    import sys
    print("Python Version",sys.version)
    print("PyQt5/PySide6 Version:",PYQT_VERSION_STR)
    print("Qt Version:",QT_VERSION_STR)
    app = QtWidgets.QApplication(sys.argv)
    w = QtWidgets.QWidget()
    w.show()
    sig=TestDynamicTupleSignal()
    app.exec()

报错信息 #

Traceback (most recent call last):
  File "c:\data\src\test.py", line 42, in <module>
    sig=TestDynamicTupleSignal()
  File "c:\data\src\test.py", line 29, in __init__
    self.dynsig.connect(self.whattheheck)
  File "c:\data\src\test.py", line 20, in connect
    self.signal.connect(func)
TypeError: connect() takes 2 positional arguments but 4 were given

版本信息 #

Python Version 3.9.5 (tags/v3.9.5:0a7dcbd, May  3 2021, 17:27:52) [MSC v.1928 64 bit (AMD64)]
PySide6 Version: 6.5.1.1
Qt Version: 6.5.1

PyQt5 Version: 5.12.3
Qt Version: 5.12.10

问题分析与解决 #

这不是PySide6的bug，是你在QObject子类中定义的connect、emit方法和父类QObject的内置方法重名了。

QObject本身就自带connect和emit方法，你自定义的方法覆盖了父类的同名方法，导致调用self.signal.connect(func)时，实际执行的是你自己写的connect方法（而非Signal对象的connect方法），但你的方法仅接受2个参数，而Signal的connect调用时会传递更多参数，因此触发参数不匹配的错误。

解决方法很简单：修改自定义方法的名称，避免和QObject的内置方法冲突。比如将connect改为connect_slot，emit改为emit_data：

修改后的代码 #

from PySide6 import QtCore,QtWidgets
from PySide6.QtCore import PYSIDE_VERSION_STR, QT_VERSION_STR


class DynamicTupleSignal(QtCore.QObject):
    signal = QtCore.Signal(tuple)

    def connect_slot(self, func):
        self.signal.connect(func)

    def emit_data(self, data):
        self.signal.emit(data)

class TestDynamicTupleSignal:
    dynsig=DynamicTupleSignal()

    def __init__(self):
        self.dynsig.connect_slot(self.whattheheck)

    def whattheheck(self,data):
        print(data)

if __name__ == "__main__":
    import sys
    print("Python Version", sys.version)
    print("PySide6 Version:", PYSIDE_VERSION_STR)
    print("Qt Version:", QT_VERSION_STR)
    app = QtWidgets.QApplication(sys.argv)
    w = QtWidgets.QWidget()
    w.show()
    sig=TestDynamicTupleSignal()
    # 测试发射信号
    sig.dynsig.emit_data(("测试内容", 123))
    app.exec()

另外，建议直接使用PySide6官方提供的版本变量PYSIDE_VERSION_STR和QT_VERSION_STR，避免重命名导致混淆。

内容的提问来源于stack exchange，提问作者Torben