我有一个小型 Python 程序,它获取 Tkinter 比例尺的值并将其放入标签中。
#!/usr/bin/python
from Tkinter import *
class App:
strval = StringVar()
def __init__(self,master):
frame = Frame(master)
frame.pack()
self.slide = Scale(frame, command = self.up, from_ = 1, to = 100)
self.out = Label(frame, textvariable = self.strval)
self.slide.pack()
self.out.pack()
def up(self,newscale):
amount = str(newscale)
self.strval.set(amount)
root = Tk()
app = App(root)
root.mainloop()
当我运行程序时,它会给我错误信息:
Traceback (most recent call last):
File "/Users/alex/Desktop/Python/Tkinter/scale_Entry.py", line 5, in <module>
class App:
File "/Users/alex/Desktop/Python/Tkinter/scale_Entry.py", line 7, in App
strval = StringVar()
File "/System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/lib-tk/Tkinter.py", line 254, in __init__
Variable.__init__(self, master, value, name)
File "/System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/lib-tk/Tkinter.py", line 185, in __init__
self._tk = master.tk
AttributeError: 'NoneType' object has no attribute 'tk'
Exception exceptions.AttributeError: "StringVar instance has no attribute '_tk'" in <bound method StringVar.__del__ of <Tkinter.StringVar instance at 0x69f238>> ignored
logout
我不太确定哪里出了问题,而且我对 Tk 接口(interface)完全一窍不通。 如果有人能解释我做错了什么,我会很高兴。
最佳答案
发生这种情况是因为您在创建 Tk 根元素之前创建了 StringVar。如果将语句 root = Tk()
移到类的定义之前,您将看到它是如何按预期工作的。
但是,理想的解决方案是以一种不依赖顺序的方式来编写它,因此我建议您在构造函数中创建 StringVar:
class App:
def __init__(self,master):
frame = Frame(master)
frame.pack()
self.strval = StringVar(frame)
# ...
关于python - 尝试从 Tkinter 比例尺中获取值并将其放入标签中,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/17257045/