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

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  • seanacais
    #1

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

    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
    Tags: None
    • Peter Otten
      #2
      Re: Using StringVars in List of Dictionaries as tkInter variables for Scale and Label widgets

      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

        Comment

        • seanacais
          #3
          Re: Using StringVars in List of Dictionaries as tkInter variables forScale and Label widgets

          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

            Comment

            • Peter Otten
              #4
              Re: Using StringVars in List of Dictionaries as tkInter variables for Scale and Label widgets

              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

                Comment

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