我现在的情况是想断言 PyQt5 信号的身份。具体来说,我想检查来自给定 QPushButton 对象的单击信号是否与存储在名为 signal 的变量中的信号相同。以下代码片段说明了这种情况:
from PyQt5.QtWidgets import QApplication, QPushButton
app = QApplication([])
widget = QPushButton()
signal = widget.clicked
widget.clicked == signal
Out[1]: False
widget.clicked is signal
Out[2]: False
id(widget.clicked) == id(signal)
Out[3]: False
如图所示,分别涉及 ==
、is
和 id()
的三个比较均产生 False
,即他们无法断言左手论证和右手论证的同一性。
有什么方法可以断言 widget.clicked
和 signal
引用相同的信号吗?
最佳答案
每次调用它时都会创建作为实体的信号,因为它们代表不同的连接:
In [1]: import sys
In [2]: from PyQt5 import QtWidgets
In [3]: app = QtWidgets.QApplication(sys.argv)
In [4]: button = QtWidgets.QPushButton()
In [5]: id(button.clicked)
Out[5]: 140150155639464
In [6]: id(button.clicked)
Out[6]: 140150154507528
In [7]: id(button.clicked)
Out[7]: 140150155640184
In [8]: id(button.clicked)
Out[8]: 140150155640504
In [9]: id(button.clicked)
Out[9]: 140150154510128
In [10]: id(button.clicked)
Out[10]: 140149427454320
因此,如果在同一个信号和槽之间连接 100 次,并且当信号发出时,槽将被调用 100 次:
import sys
from PyQt5 import QtCore, QtWidgets
def foo():
print("clicked")
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
button = QtWidgets.QPushButton("Press me")
button.show()
for _ in range(10):
button.clicked.connect(foo)
# the click is emulated
QtCore.QTimer.singleShot(1000, lambda: button.animateClick(500))
QtCore.QTimer.singleShot(2000, app.quit)
sys.exit(app.exec_())
输出:
clicked
clicked
clicked
clicked
clicked
clicked
clicked
clicked
clicked
clicked
因此不可能直接解决您的问题,但我认为您的目标是区分哪个对象发出调用插槽的信号,因为您可能有多个对象连接到同一个插槽,为此,如果有解决办法:
1。使用 sender()
方法
如果槽属于 QObject(或从 QObject 派生的类作为小部件),那么您可以使用 sender 方法来获取发出信号的对象。
import sys
from PyQt5 import QtCore, QtWidgets
class Widget(QtWidgets.QWidget):
def __init__(self, parent=None):
super(Widget, self).__init__(parent)
self.button_1 = QtWidgets.QPushButton("button 1")
self.button_1.clicked.connect(self.foo)
self.button_2 = QtWidgets.QPushButton("button 2")
self.button_2.clicked.connect(self.foo)
self.button_3 = QtWidgets.QPushButton("button 3")
self.button_3.clicked.connect(self.foo)
lay = QtWidgets.QVBoxLayout(self)
lay.addWidget(self.button_1)
lay.addWidget(self.button_2)
lay.addWidget(self.button_3)
@QtCore.pyqtSlot()
def foo(self):
button = self.sender()
if button is self.button_1:
print("button_1")
elif button is self.button_2:
print("button_2")
elif button is self.button_3:
print("button_3")
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
w = Widget()
w.show()
sys.exit(app.exec_())
2。将对象作为附加参数传递
2.1 lambda 函数 <小时/>import sys
from PyQt5 import QtCore, QtWidgets
class Widget(QtWidgets.QWidget):
def __init__(self, parent=None):
super(Widget, self).__init__(parent)
self.button_1 = QtWidgets.QPushButton("button 1")
self.button_1.clicked.connect(lambda *args, b=self.button_1 : self.foo(b))
self.button_2 = QtWidgets.QPushButton("button 2")
self.button_2.clicked.connect(lambda *args, b=self.button_2 : self.foo(b))
self.button_3 = QtWidgets.QPushButton("button 3")
self.button_3.clicked.connect(lambda *args, b=self.button_3 : self.foo(b))
lay = QtWidgets.QVBoxLayout(self)
lay.addWidget(self.button_1)
lay.addWidget(self.button_2)
lay.addWidget(self.button_3)
def foo(self, button):
if button is self.button_1:
print("button_1")
elif button is self.button_2:
print("button_2")
elif button is self.button_3:
print("button_3")
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
w = Widget()
w.show()
sys.exit(app.exec_())
2.1 functools.partial函数
<小时/>
import sys
from PyQt5 import QtCore, QtWidgets
from functools import partial
class Widget(QtWidgets.QWidget):
def __init__(self, parent=None):
super(Widget, self).__init__(parent)
self.button_1 = QtWidgets.QPushButton("button 1")
self.button_1.clicked.connect(partial(self.foo, self.button_1))
self.button_2 = QtWidgets.QPushButton("button 2")
self.button_2.clicked.connect(partial(self.foo, self.button_2))
self.button_3 = QtWidgets.QPushButton("button 3")
self.button_3.clicked.connect(partial(self.foo, self.button_3))
lay = QtWidgets.QVBoxLayout(self)
lay.addWidget(self.button_1)
lay.addWidget(self.button_2)
lay.addWidget(self.button_3)
def foo(self, button):
if button is self.button_1:
print("button_1")
elif button is self.button_2:
print("button_2")
elif button is self.button_3:
print("button_3")
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
w = Widget()
w.show()
sys.exit(app.exec_())
<小时/>
就我而言,如果可以的话,我更喜欢使用 sender,然后是 functools.partial,最后是 lambda 方法
关于python - 如何断言 PyQt5 信号的身份?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54712203/