PyQt Widget connect() and disconnect()(PyQt Widget connect() 和 disconnect())

问题描述

根据条件，我想将按钮连接/重新连接到不同的功能.

假设我有一个按钮:

myButton = QtGui.QPushButton()

在这个例子中，假设我检查是否有互联网连接.

如果连接==真:myButton.clicked.connect(function_A)elif 连接 == False:myButton.clicked.connect(function_B)

首先，在按钮被重新分配/重新连接到另一个功能(功能_A 或功能_B)之前，我想将按钮与它已经连接的任何功能断开连接.其次，我已经注意到，重新连接按钮后，需要额外单击按钮才能选择新功能.按钮重新连接到另一个功能后，它仍会尝试运行前一个功能 - 按钮先前(重新连接之前)连接到的功能.请指教.提前致谢！

稍后

似乎小部件的 .disconnect() 方法可用于将按钮与其连接的功能断开连接.

myButton.disconnect()

不幸的是，如果小部件未连接到任何函数，.disconnect() 会抛出错误.为了解决这个问题，我使用了 Try/Except.但我宁愿使用更优雅的解决方案...

尝试:myButton.clicked.disconnect()除了例外:通过

如果你需要在很多地方重新连接信号，那么你可以定义一个通用的效用函数，如下所示:

def reconnect(signal, newhandler=None, oldhandler=None):尝试:如果 oldhandler 不是 None:而真:signal.disconnect(oldhandler)别的:信号断开()除了类型错误:经过如果 newhandler 不是 None:信号.connect(newhandler)...如果连接:重新连接(myButton.clicked，function_A)别的:重新连接(myButton.clicked，function_B)

(注意:安全断开特定处理程序需要循环，因为它可能已连接多次，并且 disconnect(slot) 一次仅删除一个连接.).

Depending on a conditions I would like to connect/re-connect a button to a different function.

Let's say I have a button:

myButton = QtGui.QPushButton()

For this example let's say I check if there is an internet connection.

if connected == True:
    myButton.clicked.connect(function_A)

elif connected == False:
    myButton.clicked.connect(function_B)

First of all I would like to disconnect a button from any function it was already connected before the button is being re-assigned/re-connected to another function (function_A or function_B). Secondly, I have already noticed that after the button is re-connected it takes an extra click for the button to pick up a new function. After the button is re-connected to another function it still attempts to run a previous function - a function to which a button was connected earlier (before a re-connection). Please advice. Thanks in advance!

EDITED LATER:

It appears a widget's .disconnect() method can be used to disconnect a button from a function it it is connected.

myButton.disconnect()

Unfortunately .disconnect() throws an error if a widget is not connected to any function. To get around it I am using Try/Except. But I would rather use a more elegant solution...

try: myButton.clicked.disconnect() 
except Exception: pass

If you need to reconnect signals in many places, then you could define a generic utility function like this:

def reconnect(signal, newhandler=None, oldhandler=None):        
    try:
        if oldhandler is not None:
            while True:
                signal.disconnect(oldhandler)
        else:
            signal.disconnect()
    except TypeError:
        pass
    if newhandler is not None:
        signal.connect(newhandler)

...

if connected:
    reconnect(myButton.clicked, function_A)
else:
    reconnect(myButton.clicked, function_B)

(NB: the loop is needed for safely disconnecting a specific handler, because it may have been connected multple times, and disconnect(slot) only removes one connection at a time.).

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