Class Struggle: Connecting a Method to an Outside Variable

[Larz60+]

using myVar as a name for a widget is misleading.
the textvariable attribute should point to a tk.StringVar which you can preset using
that attribute and a tk.StringVar.
The StringVar can be set externally with string_var_name.set() (replace string_var_name with actual name)
It can be initally be set within the button definition

string_var_name = StringVar()
self.myVar = Button(self.position, text=self.text, textvariable=string_var_name, command=self.cmd)

Again, rename myVar to a meaningful widget name.
Also to be in conformance with PEP8, don't use camel case, use underscore instead
see: http://effbot.org/tkinterbook/variable.htm

Sorry for the edits, just got up