PyQt5开发：如何在函数与类外部获取folder_path变量值？

1. 程序终止导致后续代码不执行：sys.exit(app.exec_())会直接终止Python解释器，所以你写在最后的print(folder_path + 'ddd')永远不会运行。
2. 全局变量使用不当：即便用了global声明，类内部的全局变量操作在程序终止后也无法被外部访问，而且这种方式不符合面向对象的设计规范。

推荐两种可行方案，优先选择模式对话框的实现方式，更贴合“选择路径后返回结果”的场景：

方案一：改用QDialog（推荐） #

from PyQt5 import QtWidgets
import sys

class FolderSelectorDialog(QtWidgets.QDialog):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Creator")
        self.setGeometry(400, 400, 400, 200)
        
        # 初始化实例变量存储路径
        self.folder_path = ""
        self.file_path = ""
        
        # 创建布局与控件
        self.grid_layout = QtWidgets.QGridLayout(self)
        
        self.folder_line_edit = QtWidgets.QLineEdit()
        self.browse_folder_btn = QtWidgets.QPushButton("浏览文件夹")
        self.browse_folder_btn.clicked.connect(self.browse_folder)
        
        self.file_line_edit = QtWidgets.QLineEdit()
        self.browse_file_btn = QtWidgets.QPushButton("浏览文件")
        self.browse_file_btn.clicked.connect(self.browse_file)
        
        self.submit_button = QtWidgets.QPushButton("提交")
        self.submit_button.clicked.connect(self.accept)
        
        self.exit_button = QtWidgets.QPushButton("退出")
        self.exit_button.clicked.connect(self.reject)
        
        # 添加控件到布局
        self.grid_layout.addWidget(self.folder_line_edit, 0, 0)
        self.grid_layout.addWidget(self.browse_folder_btn, 0, 1)
        self.grid_layout.addWidget(self.file_line_edit, 1, 0)
        self.grid_layout.addWidget(self.browse_file_btn, 1, 1)
        self.grid_layout.addWidget(self.submit_button, 2, 0)
        self.grid_layout.addWidget(self.exit_button, 2, 1)

    def browse_folder(self):
        options = QtWidgets.QFileDialog.Options()
        options |= QtWidgets.QFileDialog.ReadOnly
        folder_path = QtWidgets.QFileDialog.getExistingDirectory(self, "选择文件夹", options=options)
        if folder_path:
            self.folder_path = folder_path
            self.folder_line_edit.setText(folder_path)

    def browse_file(self):
        options = QtWidgets.QFileDialog.Options()
        options |= QtWidgets.QFileDialog.ReadOnly
        file_path, _ = QtWidgets.QFileDialog.getOpenFileName(self, "选择文件", options=options)
        if file_path:
            self.file_path = file_path
            self.file_line_edit.setText(file_path)

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    dialog = FolderSelectorDialog()
    # 以模式对话框显示，关闭后返回结果
    result = dialog.exec_()
    if result == QtWidgets.QDialog.Accepted:
        # 提交按钮被点击后，直接从实例获取路径
        print(dialog.folder_path + 'ddd')
        print(dialog.file_path)

方案二：保留QMainWindow，修改程序流程 #

from PyQt5 import QtWidgets
import sys

class MyApp(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Creator")
        self.setGeometry(400, 400, 400, 200)
        
        # 初始化实例变量存储路径
        self.folder_path = ""
        self.file_path = ""
        
        self.central_widget = QtWidgets.QWidget()
        self.setCentralWidget(self.central_widget)
        self.grid_layout = QtWidgets.QGridLayout(self.central_widget)
        
        self.folder_line_edit = QtWidgets.QLineEdit()
        self.browse_folder_btn = QtWidgets.QPushButton("浏览文件夹")
        self.browse_folder_btn.clicked.connect(self.browse_folder)
        
        self.file_line_edit = QtWidgets.QLineEdit()
        self.browse_file_btn = QtWidgets.QPushButton("浏览文件")
        self.browse_file_btn.clicked.connect(self.browse_file)
        
        self.submit_button = QtWidgets.QPushButton("提交")
        self.submit_button.clicked.connect(self.close)
        
        self.exit_button = QtWidgets.QPushButton("退出")
        self.exit_button.clicked.connect(self.close)
        
        self.grid_layout.addWidget(self.folder_line_edit, 0, 0)
        self.grid_layout.addWidget(self.browse_folder_btn, 0, 1)
        self.grid_layout.addWidget(self.file_line_edit, 1, 0)
        self.grid_layout.addWidget(self.browse_file_btn, 1, 1)
        self.grid_layout.addWidget(self.submit_button, 2, 0)
        self.grid_layout.addWidget(self.exit_button, 2, 1)

    def browse_folder(self):
        options = QtWidgets.QFileDialog.Options()
        options |= QtWidgets.QFileDialog.ReadOnly
        folder_path = QtWidgets.QFileDialog.getExistingDirectory(self, "选择文件夹", options=options)
        if folder_path:
            self.folder_path = folder_path
            self.folder_line_edit.setText(folder_path)

    def browse_file(self):
        options = QtWidgets.QFileDialog.Options()
        options |= QtWidgets.QFileDialog.ReadOnly
        file_path, _ = QtWidgets.QFileDialog.getOpenFileName(self, "选择文件", options=options)
        if file_path:
            self.file_path = file_path
            self.file_line_edit.setText(file_path)

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    main_window = MyApp()
    main_window.show()
    # 去掉sys.exit，让app.exec_()返回后继续执行后续代码
    app.exec_()
    # 窗口关闭后，直接访问实例的属性
    print(main_window.folder_path + 'ddd')

• 放弃global变量，改用类的实例属性（self.folder_path）存储路径，符合面向对象设计逻辑，也便于后续访问。
• sys.exit(app.exec_())会直接终止程序，必须去掉sys.exit，让app.exec_()执行完毕后继续处理后续代码。
• QDialog的模式对话框更适合这类“选择后返回结果”的场景，代码逻辑更清晰，无需额外处理窗口生命周期。

内容的提问来源于stack exchange，提问作者Rose