pyqt的问题，自定义事件不能connectSlotsByName 吗

import sys,
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtCore import Qt, QObject, pyqtSignal, pyqtSlot
from PyQt5.QtWidgets import QApplication, ,QWidget
####
class abc(QWidget):
p1 = pyqtSignal()
class aa(QWidget):
def __init__(self, parent = None):
super(aa, self).__init__(parent)
self.a = abc()
self.a.setObjectName('a')
QtCore.QMetaObject.connectSlotsByName(self.a) # 没反应
#self.a.p1.connect(self.on_a_p1)
self.a.p1.emit()
@pyqtSlot()
def on_a_p1(self):
print('p1')
App = QApplication(sys.argv)
a1=aa()
print('end')
sys.exit(App.exec())
用 QtCore.QMetaObject.connectSlotsByName(self.a) 没反应
只能手工 connect ,有办法解决吗