python3-tkinter模块错误笔记-text，entry等找不到相应方法

错误日志：

    file_path = f_name.get()
AttributeError: 'NoneType' object has no attribute 'get'

代码：

f_name = tkinter.Entry().pack(side='left', expand=True, fill='both')

应该定义和布局进行分开：

f_name = tkinter.Entry()
f_name.pack(side='left', expand=True, fill='both')

简单的gui文本编辑器学习代码：

import tkinter
from tkinter.scrolledtext import ScrolledText

top = tkinter.Tk()
top.title('FileAction')


def load():
    file_path = f_name.get()
    print(file_path)
    with open(file_path, 'r', encoding='utf-8')as f:
        text.delete(0.0, 'end')
        text.insert('insert', f.read())


def save():
    file_path = f_name.get()
    print(file_path)
    with open(file_path, 'w', encoding='utf-8')as f:
        f.write(text.get('1.0', 'end'))


label = tkinter.Label(text='请输入文件路径：').pack()
text = ScrolledText()
text.pack(side='bottom', expand=True, fill='both')

f_name = tkinter.Entry()
f_name.pack(side='left', expand=True, fill='both')

b_save = tkinter.Button(text='save', command=save).pack(side='left')
b_open = tkinter.Button(text='open', command=load).pack(side='left')

top.mainloop()