Stupid Python Ideas

There are a lot of questions on StackOverflow asking "what's the deal with self?"

Many of them are asking a language-design question: Why does Python require explicit self when other languages like C++ and friends (including Java), JavaScript, etc. do not? Guido has answered that question many times, most recently in Why explicit self has to stay.

But some people are asking a more practical question: Coming from a different language (usually Java), they don't know how to use self properly.

Tkinter makes slapping together a simple GUI very easy. But unfortunately, many of its features aren't very well documented. The only way to figure out how to do something is often to figure out what Tk objects it's using, look up the Tcl/Tk documentation for those objects, then try to work out how to access them through the Tkinter layer.

One of the places this most often comes up is validating Entry boxes.

In Python 2.x Tkinter code, you see a lot of stuff like this:

class MyFrame(Frame): def __init__(self, parent, n): Frame.__init__(self, parent) self.n = n Why?

Inheritance and overriding

Some people start on Tkinter before getting far enough into learning Python. You should definitely read the Classes chapter in the Python tutorial, but I'll summarize the basics.

First, you're subclassing (inheriting from) the Tkinter class Frame.