環境：py2.7.14 + pyqt4
1.在使用下列方式創建信號連接時
self.connect(button, QtCore.SIGNAL('clicked()'),self.slot1(arg))
報錯提示爲：
TypeError: arguments did not match any overloaded call:
QObject.connect(QObject, SIGNAL(), QObject, SLOT(), Qt.ConnectionType=Qt.AutoConnection): argument 3 has unexpected type 'NoneType'
QObject.connect(QObject, SIGNAL(), callable, Qt.ConnectionType=Qt.AutoConnection): argument 3 has unexpected type 'NoneType'
QObject.connect(QObject, SIGNAL(), SLOT(), Qt.ConnectionType=Qt.AutoConnection): argument 3 has unexpected type 'NoneType'
解析：
這裏的slot1()是一個函數，當槽函數是自定義的函數時要這樣，用lambda: self.slot1(arg)替換self.slot1(arg)即可
或者這個slot1只是一個method，不需要參數時，用slot1替換slot即可。
看到這，其本質是python調用函數時加不加括號的區別。
def ab():
return 1+2
print ab
print ab()
結果：
<function ab at 0x00000000035AB748>
3
綜上，其區別在與不加括號時，調用的時這個函數的，這個對象的內存地址，
加括號時你調用的是這個函數的運行結果
參考StackOverflow：
person a:The connect() method expects a callable argument. When you write self.Soft_Memory() you are making a call to that method, and the result of that call (None, since you don't explicitly return anything) is what is being passed to connect().
person b:You want to pass a reference to the method itself.
you should use a reference of the method, instead of calling it:
self.PB1.clicked.connect(self.Soft_Memory)
However, you might often need to pass arguments on those functions (I certainly do). On those situations, if you need to use args there's a workaround by using lambda.
self.PB1.clicked.connect(lambda: myfunction(self, arg1, True, "example", arg4))
參考鏈接：
https://stackoverflow.com/questions/45793966/clicked-connect-error