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Question

我Python和PyQt4很新。
我想問"How to back to previous Window ?"
我有2個文件在這裏，文件 '登錄' 和 '註冊'

here file login.py

import sys 
from PyQt4.QtGui import QWidget, QPushButton, QLineEdit, QLabel, \ 
         QApplication, QGridLayout 

from signup import SignUp 


class Login(QWidget): 
    def __init__(self): 
     super(Login, self).__init__() 

     self.setWindowTitle("Login") 

     self.login_window() 

    def login_window(self): 
     self.login_layout = QGridLayout() 

     self.login_button = QPushButton("Login") 
     self.signup_button = QPushButton("Sign Up") 

     self.login_layout.addWidget(self.login_button, 2, 0) 
     self.login_layout.addWidget(self.signup_button, 2, 1) 

     self.signup_button.clicked.connect(self.signup_show) 

     self.setLayout(self.login_layout) 
     self.show() 

    def signup_show(self): 
     self.signupshow = SignUp() 
     self.hide() 
     self.signupshow.show() 

    def check_signup(self): 
     SignUp.check_signup() 
     self.show() 


def main(): 
    app = QApplication(sys.argv) 
    login = Login() 
    sys.exit(app.exec_()) 

if __name__ == '__main__': 
    main() 

and here is signup.py

import sys 
from PyQt4.QtGui import QWidget, QPushButton, QLineEdit, QLabel, \ 
         QApplication, QGridLayout 


class SignUp(QWidget): 
    def __init__(self): 
     super(SignUp, self).__init__() 

     self.setWindowTitle("Sign Up") 

     self.signup_window() 

    def signup_window(self): 

     self.signup_layout = QGridLayout() 
     self.signup_button = QPushButton("Sign Up") 
     self.signup_layout.addWidget(self.signup_button, 2, 0, 1, 0) 
     self.signup_button.clicked.connect(self.check_signup) 
     self.setLayout(self.signup_layout) 
     self.show() 

    def check_signup(self): 
     self.close() 

def main(): 
    app = QApplication(sys.argv) 
    signup = SignUp() 
    sys.exit(app.exec_()) 

if __name__ == '__main__': 
    main() 

我的問題是，什麼時候按鈕signup from signup.py，它是關閉的但窗口登錄不顯示。
我想我沒有在任何signup.py爲trigger在check_signup login.py
在這段代碼中，我刪除一些Line Edit和Label。我認爲這不是問題。
我希望有人可以幫助，謝謝:)之前
，如果你回答這個questtion，我希望你能解釋的邏輯一點，再次謝謝:)

Answer 1

我真的不知道是什麼你試圖達到（你的描述有點混亂），但是讓我們從這裏開始。我把所有的代碼在一個文件，因爲你需要import對方（這會導致循環進口）。然後，我剛添加這兩行

self.login = Login() 
self.login.show() 

成SignUp類的check_signup方法，其彈出式窗口Login。如果這不是您想要的結果，請告訴我們並提供更好的描述。代碼如下：

import sys 
from PyQt4.QtGui import QWidget, QPushButton, QLineEdit, QLabel, \ 
         QApplication, QGridLayout 

class Login(QWidget): 
    def __init__(self): 
     super(Login, self).__init__() 

     self.setWindowTitle("Login") 

     self.login_window() 

    def login_window(self): 
     self.login_layout = QGridLayout() 

     self.login_button = QPushButton("Login") 
     self.signup_button = QPushButton("Sign Up") 

     self.login_layout.addWidget(self.login_button, 2, 0) 
     self.login_layout.addWidget(self.signup_button, 2, 1) 

     self.signup_button.clicked.connect(self.signup_show) 

     self.setLayout(self.login_layout) 
     self.show() 

    def signup_show(self): 
     self.signupshow = SignUp() 
     self.hide() 
     self.signupshow.show() 

    def check_signup(self): 
     SignUp.check_signup() 
     self.show() 


class SignUp(QWidget): 
    def __init__(self): 
     super(SignUp, self).__init__() 

     self.setWindowTitle("Sign Up") 

     self.signup_window() 

    def signup_window(self): 

     self.signup_layout = QGridLayout() 
     self.signup_button = QPushButton("Sign Up") 
     self.signup_layout.addWidget(self.signup_button, 2, 0, 1, 0) 
     self.signup_button.clicked.connect(self.check_signup) 
     self.setLayout(self.signup_layout) 
     self.show() 

    def check_signup(self): 
     self.login = Login() 
     self.login.show() 
     self.close() 

def main(): 
    app = QApplication(sys.argv) 
    signup = SignUp() 
    sys.exit(app.exec_()) 

if __name__ == '__main__': 
    main() 

Answer 2

你還是使用信號槽連接：

import sys 
from PyQt4 import QtGui, QtCore 


class WidgetA(QtGui.QWidget): 
    open_b = QtCore.pyqtSignal() 

    def __init__(self, parent=None): 
     super(WidgetA, self).__init__(parent) 
     self.resize(100, 100) 
     self.l = QtGui.QVBoxLayout() 
     self.close_btn = QtGui.QPushButton('Close') 
     self.b_btn = QtGui.QPushButton('Open B') 
     self.b_btn.clicked.connect(self.b_btn_clicked) 
     self.l.addWidget(self.close_btn) 
     self.l.addWidget(self.b_btn) 
     self.setLayout(self.l) 

    def b_btn_clicked(self): 
     self.open_b.emit() 
     self.hide() 


class WidgetB(QtGui.QWidget): 
    open_a = QtCore.pyqtSignal() 

    def __init__(self, parent=None): 
     super(WidgetB, self).__init__(parent) 
     self.resize(100, 100) 
     self.l = QtGui.QVBoxLayout() 
     self.close_btn = QtGui.QPushButton('Close') 
     self.close_btn.clicked.connect(self.hide) 
     self.a_btn = QtGui.QPushButton('Open A') 
     self.a_btn.clicked.connect(self.a_btn_clicked) 
     self.l.addWidget(self.close_btn) 
     self.l.addWidget(self.a_btn) 
     self.setLayout(self.l) 

    def a_btn_clicked(self): 
     self.open_a.emit() 
     self.hide() 


def main(): 
    app = QtGui.QApplication(sys.argv) 
    a = WidgetA() 
    b = WidgetB() 
    a.open_b.connect(lambda: b.show()) 
    b.open_a.connect(lambda: a.show()) 
    a.show() 
    sys.exit(app.exec_()) 


if __name__ == '__main__': 
    main()