Using StringVars in List of Dictionaries as tkInter variables forScale and Label widgets

[seanacais]

I'm trying to build an unknown number of repeating gui elements
dynamically so I need to store the variables in a list of
dictionaries. I understand that Scale "variable" name needs to be a
StringVar but I cannot figure out how to initialize the dictionary.

I've tried the following code

ps = PowerSupply() # Instantiate a Power Supply VM Object
numOPs = ps.getOnum() # Find the number of outputs
OPValues = [] # Global list to hold one dictionary per output

for c in range(numOPs):
OPValues.append ({ })
ps.initOPValues (c, OPValues[c])

ps.initOPValues is defined as follows:

def initOPValues(se lf, OPname, dname):

OPDefaults = {
'Vval' : 0,
'Ival' : 0,
'Otemp' : 0
}

dname = dict((d,StringV ar()) for d in OPDefaults)
for d in OPDefaults:
dname[d].set(OPDefaults[d])

I get the following error:

Traceback (most recent call last):
File "C:\Code\gui\tk inter.py", line 165, in <module>
ps.initOPValues (c, OPValues[c])
File "C:\Code\gui\tk inter.py", line 47, i initOPValues
dname = dict((d,StringV ar()) for d in OPDefaults)
File "C:\Code\gui\tk inter.py", line 47, in <genexpr>
dname = dict((d,StringV ar()) for d in OPDefaults)
File "C:\Python25\li b\lib-tk\Tkinter.py", line 254, in __init__
Variable.__init __(self, master, value, name)
File "C:\Python25\li b\lib-tk\Tkinter.py", line 185, in __init__
self._tk = master.tk
AttributeError: 'NoneType' object has no attribute 'tk'
Exception exceptions.Attr ibuteError: "StringVar instance has no
attribute '_tk'"
in <bound method StringVar.__del __ of <Tkinter.String Var instance at
0x00B7D468>igno red

Any help is appreciated!

Thanks,

Kevin

[Peter Otten]

seanacais wrote:

I'm trying to build an unknown number of repeating gui elements
dynamically so I need to store the variables in a list of
dictionaries. I understand that Scale "variable" name needs to be a
StringVar but I cannot figure out how to initialize the dictionary.

I've tried the following code

ps = PowerSupply() # Instantiate a Power Supply VM Object
numOPs = ps.getOnum() # Find the number of outputs
OPValues = [] # Global list to hold one dictionary per output

for c in range(numOPs):
OPValues.append ({ })
ps.initOPValues (c, OPValues[c])

ps.initOPValues is defined as follows:

def initOPValues(se lf, OPname, dname):

OPDefaults = {
'Vval' : 0,
'Ival' : 0,
'Otemp' : 0
}

dname = dict((d,StringV ar()) for d in OPDefaults)
for d in OPDefaults:
dname[d].set(OPDefaults[d])

I get the following error:

Traceback (most recent call last):
File "C:\Code\gui\tk inter.py", line 165, in <module>
ps.initOPValues (c, OPValues[c])
File "C:\Code\gui\tk inter.py", line 47, i initOPValues
dname = dict((d,StringV ar()) for d in OPDefaults)
File "C:\Code\gui\tk inter.py", line 47, in <genexpr>
dname = dict((d,StringV ar()) for d in OPDefaults)
File "C:\Python25\li b\lib-tk\Tkinter.py", line 254, in __init__
Variable.__init __(self, master, value, name)
File "C:\Python25\li b\lib-tk\Tkinter.py", line 185, in __init__
self._tk = master.tk
AttributeError: 'NoneType' object has no attribute 'tk'
Exception exceptions.Attr ibuteError: "StringVar instance has no
attribute '_tk'"
in <bound method StringVar.__del __ of <Tkinter.String Var instance at
0x00B7D468>igno red

Any help is appreciated!

There's some magic going on behind the scene which means that you have to
create a Tkinter.Tk instance before you can start churning out StringVars:

>>import Tkinter as tk
v = tk.StringVar()

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.5/lib-tk/Tkinter.py", line 257, in __init__
Variable.__init __(self, master, value, name)
File "/usr/lib/python2.5/lib-tk/Tkinter.py", line 188, in __init__
self._tk = master.tk
AttributeError: 'NoneType' object has no attribute 'tk'

>>root = tk.Tk()
v = tk.StringVar()
v.set(42)
v.get()

'42'

Peter

[seanacais]

On May 19, 2:11 pm, Peter Otten <__pete...@web. dewrote:

>
There's some magic going on behind the scene which means that you have to
create a Tkinter.Tk instance before you can start churning out StringVars:

>import Tkinter as tk
v = tk.StringVar()

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.5/lib-tk/Tkinter.py", line 257, in __init__
Variable.__init __(self, master, value, name)
File "/usr/lib/python2.5/lib-tk/Tkinter.py", line 188, in __init__
self._tk = master.tk
AttributeError: 'NoneType' object has no attribute 'tk'>>root = tk.Tk()

>v = tk.StringVar()
v.set(42)
v.get()

'42'

Peter

I had the Tkinter import as

from Tkinter import * but I changed it to

import Tkinter as tk

and modified the creation of the root object to

root=tk.Tk()

I then had to change every instance of Menu, Label,
Button, and all Tkinter elements to be prefaced by
tk. (so Button became tk.Button). That kind of makes
sense to me.

However even after specifying StringVar is a tk type

def initOPValues(se lf, OPname, dname):

OPDefaults = {
'Vval' : 0,
'Ival' : 0,
'Otemp' : 0
}

dname = dict((d,tk.Stri ngVar()) for d in OPDefaults)
for d in OPDefaults:
dname[d].set(OPDefaults[d])
I still get a very similar error message

C:\Code\gui>tki nter.py
Traceback (most recent call last):
File "C:\Code\gui\tk inter.py", line 169, in <module>
ps.initOPValues (c, OPValues[c])
File "C:\Code\gui\tk inter.py", line 54, in initOPValues
dname = dict((d,tk.Stri ngVar()) for d in OPDefaults)
File "C:\Code\gui\tk inter.py", line 54, in <genexpr>
dname = dict((d,tk.Stri ngVar()) for d in OPDefaults)
File "C:\Python25\li b\lib-tk\Tkinter.py", line 254, in __init__
Variable.__init __(self, master, value, name)
File "C:\Python25\li b\lib-tk\Tkinter.py", line 185, in __init__
self._tk = master.tk
AttributeError: 'NoneType' object has no attribute 'tk'
Exception exceptions.Attr ibuteError: "StringVar instance has no
attribute '_tk'"
in <bound method StringVar.__del __ of <Tkinter.String Var instance at
0x00B7E418>igno red
Thanks!

Kevin

[Peter Otten]

seanacais wrote:

I had the Tkinter import as

from Tkinter import * but I changed it to

import Tkinter as tk

and modified the creation of the root object to

root=tk.Tk()

I then had to change every instance of Menu, Label,
Button, and all Tkinter elements to be prefaced by
tk. (so Button became tk.Button). That kind of makes
sense to me.

However even after specifying StringVar is a tk type

You misunderstood. There is no such thing as a "tk type".
Whether you use

from Tkinter import *

or

import Tkinter as tk

is irrelevant for the problem at hand.

def initOPValues(se lf, OPname, dname):

OPDefaults = {
'Vval' : 0,
'Ival' : 0,
'Otemp' : 0
}

dname = dict((d,tk.Stri ngVar()) for d in OPDefaults)
for d in OPDefaults:
dname[d].set(OPDefaults[d])
I still get a very similar error message

You have to ensure that the lines

from Tkinter import *
root = Tk()

are *executed* before the line

dname = dict((d, StringVar()) for d in OPDefaults)

While I prefer the alternative

import Tkinter as tk
root = tk.Tk()
# ...
dname = dict((d, tk.StringVar()) for d in OPDefaults)

this is just a matter of style.

Peter

PS: If you still can't fix your script, please post it completely or,
better, a small self-contained (runnable) script showing the same problem