Grid and Pack in Main and Class?

It is a best practice to use both grid and pack within an application.

The only caveat is that you cannot mix them within a given frame. The choice of geometry manager (grid, pack, place) for widgets in a frame is completely independent of the geometry manger used in any other frame. Each has strengths and weaknesses, and you should use them accordingly.

Also -- and I see this mistake all the time -- a class that inherits from a widget should not call grid or pack or place on itself.

For example, this is incorrect:

class Example(tk.Frame):    def __init__(self, parent):        ...        self.pack(...)class Main(tk.Frame):    def __init__(self, parent):        ...        this.example = Example(self)

Instead of the above, pack should be removed from Example, and Main should be redefined to call pack (or grid or place):

class Main(tk.Frame):    def __init__(self, parent):        ...        this.example = Example(self)        this.example.pack(...)

The problem with the first (incorrect) example is that if you have a dozen frames inside of main along with some other widgets, if you decide to switch from pack to grid, you'll have to modify a dozen other classes. By having a parent responsible for arranging it's own children, when you make a layout change, you only have to change a single function.