Python / Tkinter Is there a way to distinguish a programmatic change to a combo box from a user initiated change? -


i'm building gui front-end network appliance many of parameters (parameter1 , parameter2 example) best displayed combo box. there implicit hierarchy of parameters parameter1 change value of parameter2, parameter2 not change parameter1 , parameter2 may changed independently.

i can trap user initiated change parameter1 , parameter2, when user initiated change parameter1 causes programmatic change parameter2 trap on parameter2 invoked.

is there clever way work around this?

sample code:

  import tkinter tk   import ttk    global parameter1   global parameter2   global list1   global list2    list1 = ["apple","bananna","orange"]   list2 = ["moe","larry","curly"]    def parameter1_changed(arg1,arg2,arg3):       print "selection list 1 changed"       print "arg1=%s  arg2=%s  arg3=%s"%(arg1,arg2,arg3)       parameter2.set(list2[1])    def parameter2_changed(arg1,arg2,arg3):       print "selection list 2 changed"       print "arg1=%s  arg2=%s  arg3=%s"%(arg1,arg2,arg3)    root = tk.tk()    parameter1 = tk.stringvar()   parameter1.set(list1[0])    parameter2=tk.stringvar()   parameter2.set(list2[0])    tk.label(root,text="list #1").grid(row=0,column=0,sticky=tk.e)   ttk.combobox(root,values=list1,textvariable=parameter1,state='readonly').grid(row=0,column=1,sticky=tk.w)   tk.label(root,text="list #2").grid(row=1,column=0,sticky=tk.e)   ttk.combobox(root,values=list2,textvariable=parameter2,state='readonly').grid(row=1,column=1,sticky=tk.w)    parameter1.trace("w",parameter1_changed)   parameter2.trace("w",parameter2_changed)    root.mainloop()

you create subclass of stringvar allows disable callback triggers:

import tkinter tk import ttk  global parameter1 global parameter2 global list1 global list2  class suppressablestingvar(tk.stringvar):     def __init__(self, *args, **kargs):         tk.stringvar.__init__(self, *args, **kargs)         self.silenced = false     def trace(self, mode, callback):         conditional_callback = lambda *args, **kargs: callback(*args, **kargs) if not self.silenced else none         tk.stringvar.trace(self, mode, conditional_callback)     def set(self, value, suppress_callback = false):         if suppress_callback:             self.silenced = true         tk.stringvar.set(self, value)         self.silenced = false   list1 = ["apple","bananna","orange"] list2 = ["moe","larry","curly"]  def parameter1_changed(arg1,arg2,arg3):   print "selection list 1 changed"   print "arg1=%s  arg2=%s  arg3=%s"%(arg1,arg2,arg3)   parameter2.set(list2[1], true)  def parameter2_changed(arg1,arg2,arg3):   print "selection list 2 changed"   print "arg1=%s  arg2=%s  arg3=%s"%(arg1,arg2,arg3)  root = tk.tk()  parameter1 = tk.stringvar() parameter1.set(list1[0])  parameter2=suppressablestingvar() parameter2.set(list2[0])  tk.label(root,text="list #1").grid(row=0,column=0,sticky=tk.e) ttk.combobox(root,values=list1,textvariable=parameter1,state='readonly').grid(row=0,column=1,sticky=tk.w) tk.label(root,text="list #2").grid(row=1,column=0,sticky=tk.e) ttk.combobox(root,values=list2,textvariable=parameter2,state='readonly').grid(row=1,column=1,sticky=tk.w)  parameter1.trace("w",parameter1_changed) parameter2.trace("w",parameter2_changed)  root.mainloop()

manipulating first dropdown produces output:

selection list 1 changed arg1=py_var0  arg2=  arg3=w

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