(Python version: 3.1.1)
I am having a strange problem with StringVar in tkinter. While attempting to continuously keep a Message widget updated in a project, I kept getting an error while trying to create the variable. I jumped out to an interactive python shell to investigate and this is what I got:
>>> StringVar <class 'tkinter.StringVar'> >>> StringVar() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python31\lib\tkinter\__init__.py", line 243, in __init__ Variable.__init__(self, master, value, name) File "C:\Python31\lib\tkinter\__init__.py", line 174, in __init__ self._tk = master.tk AttributeError: 'NoneType' object has no attribute 'tk' >>>
Any ideas? Every example I have seen on tkinter usage shows initializing the variable with nothing sent to the constructor so I am at a loss if I am missing something...
StringVar needs a master:
>>> StringVar(Tk()) <Tkinter.StringVar instance at 0x0000000004435208> >>>
or more commonly:
>>> root = Tk() >>> StringVar() <Tkinter.StringVar instance at 0x0000000004435508>
When you instantiate Tk a new interpreter is created. Before that nothing works:
>>> from Tkinter import * >>> StringVar() Traceback (most recent call last): File "<input>", line 1, in <module> File "C:\Python26\lib\lib-tk\Tkinter.py", line 251, in __init__ Variable.__init__(self, master, value, name) File "C:\Python26\lib\lib-tk\Tkinter.py", line 182, in __init__ self._tk = master.tk AttributeError: 'NoneType' object has no attribute 'tk' >>> root = Tk() >>> StringVar() <Tkinter.StringVar instance at 0x00000000044C4408>
The problem with the examples you found is that probably in the literature they show only partial snippets that are supposed to be inside a class or in a longer program so that imports and other code are not explicitly indicated.
