问当QPlainTextEdit达到一定长度时运行方法

EN

import sys

from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *

class Status(QDialog):
    def __init__(self, parent=None):
        super(Status, self).__init__(parent)

        self.label = QLabel()

        self.btn = QPushButton("Input Data")
        self.btn.clicked.connect(self.populate_row)

        self.layout = QVBoxLayout()

        self.layout.addWidget(self.btn)
        self.layout.addWidget(self.label)

        self.resize(660, 260)
        self.setLayout(self.layout)

    def populate_row(self, letter):
        self.dialog = QDialog()

        self.dialog.resize(660, 260)

        self.textBox = QPlainTextEdit(self.dialog)

        Rbtn = QPushButton("Add Data")
        Rbtn.clicked.connect(
            lambda: self.enter_data(self.textBox.toPlainText()))

        layout = QVBoxLayout(self.dialog)
        layout.addWidget(self.textBox)
        layout.addWidget(Rbtn)

        self.dialog.exec_()

    def enter_data(self, text):
        self.label.setText(text)

        lst = text.split("\n")
        try:
            for  x in lst:
                if x != "":
                    print(x)
                    self.do_something_with_x()
        except IndexError:
            pass

        self.update_data()

        self.dialog.close()

    def do_something_with_x(self):
        print('Something done with x..')

    def update_data(self):
        print('Data updated..')

if __name__ == "__main__":
    app = QApplication(sys.argv)
    ex = Status()
    ex.show()
    sys.exit(app.exec_())