Eric Brunel wrote: > On Wed, 24 Aug 2005 15:07:27 GMT, William Gill <[EMAIL PROTECTED]> wrote: > >> Working with tkinter, I have a createWidgets() method in a class. >> Within createWidgets() I create several StringVars() and >> assign them to the textvariable option of several widgets. >> Effectively my code structure is: >> >> def createWidgets(self): >> ... >> var = StringVar() >> Entry(master,textvariable=var) >> ... >> ... >> >> Though 'var' would normally go out of scope when createWidgets >> completes, since the Entry and its reference do not go out of scope, >> only the name 'var' goes out of scope, not the StringVar object, Right? > > > Well, apparently not: > > ------------------------------------------------ > from Tkinter import * > > class MyStringVar(StringVar): > def __del__(self): > print "I'm dying!" > > root = Tk() > > def cw(): > var = MyStringVar() > Entry(root, textvariable=var).pack() > > cw() > > root.mainloop() > ------------------------------------------------ > > Running this script actually prints "I'm dying!", so there is obviously > no reference from the Entry widget to the variable object. The reference > is actually kept at tcl level between an entry and the *tcl* variable, > which knows nothing about the *Python* variable. I will have to do some experimenting. > > BTW, the whole purpose of StringVar's is to be kept so that the text for > the entry can be retrieved or modified by another part of the program. > So what can be the purpose of creating variables in a function or method > and not keeping them anywhere else than a local variable? I was trying to keep my question simple. In actuality, I have a widget I'll call dataForm that extends tkSimpleDialog.Dialog. In it I have several entry and checkbox widgets, and a call to a changed() method passed from the parent. When I'm done editing dataForm, all the variables are processed in a save() method, and dataForm is destroyed.
What happened when I used self.var = MyStringVar() and Entry(root, textvariable=self.var).pack(), is that a subsequent call to create a dataForm instance has residual data from the previous instance AND the change callback caused an error. Changing to local variables seemed to cure the problems. I just tried changing back to the self.var approach, and it seems to work fine??? I must have had some name conflicts in my earlier code. I'll try to figure it out, and post if I do. Bill -- http://mail.python.org/mailman/listinfo/python-list
