Page 393 -

localize functionality

Functions inside of functions inside
of functions inside of functions...
now, that‛s what I call complexity. Of Frank: A function inside a function? Surely that’s not legal?
course, everything‛s local, you know.
Jim: Well... it depends on the programming language.
Joe: Don’t tell me this is something that only works with Python?!?

Jim: No... there are lots of programming languages that allow you
to put a function inside another function.
Frank: Name one (other than Python)!

Jim: Pascal.
Frank: Pasc... what?!?
Jim: Look, it really doesn’t matter which programming language
supports this feature. What is important is that we can do it.
Frank: And by “we” you mean “Python.”
Jim: OK, yes. Python can do it.
Frank: That’s all I was trying to say...

Joe: So, this is cool how?
Jim: Because it lets you localize functionality and handle complexity.
Joe: What?!?
Jim: Look: if a function gets big and complex, it can help to break
the function down into a collection of smaller functions, just like we
do when programs get big. We can keep the functionality local to the
Frank code that needs it inside the function. That way, we keep things as
simple as we can
Joe Joe: Even if the code itself is complex?
Jim
Frank: Like the GUI-building code we are working on now?
Jim: Yes.
Frank: OK. A function of functions it is, then. I’m all for keeping it
simple, stupid. ;-)
Joe: Yes, I like KISS, too.
Jim: Yeah... their last album was really something special, wasn’t it?

Frank & Joe: Eh?!?

358 Chapter 10