如何查找信号是否连接到任何东西

Question

有没有办法判断信号是否已连接到某个功能？

即我想看看signals.siSelectionChange是否连接到任何东西

signals.siSelectionChange.connect( self.SelAsSiAssets )

Answer 1

您可以使用QObject.receivers获取连接功能的计数.我用它如下,在closeEvent()QWidget中,我用作窗口:

    receiversCount = self.receivers(QtCore.SIGNAL("siSelectionChanged()"))
    if receiversCount > 0:
        self.sigChanged.disconnect()

请注意,参数字符串中的签名必须与真实签名匹配.

Answer 2

因为我用 PyQt5 尝试过，但似乎不存在QtCore.SIGNAL. 我用isSignalConnectedQObject的方法尝试了一下。QMetaMethod.fromSignal使用此选项时您将面临的另一个问题是PyQt5 库中没有。

结果我写了一个getSignal函数。

from PyQt5.QtCore import QMetaMethod
from PyQt5.QtCore import QObject

def getSignal (oObject : QObject, strSignalName : str):
    oMetaObj = oObject.metaObject()
    for i in range (oMetaObj.methodCount()):
        oMetaMethod = oMetaObj.method(i)
        if not oMetaMethod.isValid():
            continue
        if oMetaMethod.methodType () == QMetaMethod.Signal and \
            oMetaMethod.name() == strSignalName:
            return oMetaMethod

    return None


from PyQt5.QtCore import pyqtSignal

if __name__ == "__main__":
    class A (QObject):
        sigB = pyqtSignal()
        def __init__ (self):
            super().__init__()

    oA = A ()

    print ("is 'sigB' connected:", oA.isSignalConnected (getSignal(oA, "sigB")))

    oA.sigB.connect (lambda : print("sigB emitted!"))
    oA.sigB.emit()

    print ("is 'sigB' connected:", oA.isSignalConnected (getSignal(oA, "sigB")))

输出：

is 'sigB' connected: False
sigB emitted!
is 'sigB' connected: True