Python introduction

Welcome to Python.

def Hello():
	print 'Hello World'
if __name__=='__main__':
	Hello()

"def" makes a function, named Hello, that takes no parameters. That function has one line, which is a simple statement.

The third line, "if...", detects if the file is being interpreted at top-level (in a sense, it defines the entry point for your program). If so, it invokes the newly-defined Hello function.

Indentation is significant--all the code in a block must be indented the same distance. This avoids the { { } } of C, or the ( ( ) ) of LISP.

Python is an interpreted programming language--it remembers names and the data attached to them. So "def" creates a function object, associates it with the name Hello, and stores that in a dictionary somewhere. Find the "Interactive Window", hit Enter till you see ">>> " at the bottom, then type "dir()" and hit Enter again. You should see something like this: "['Hello', '__builtins__', '__doc__', '__name__', 'pywin']" Type Hello(), and it'll run the function again.

A variable can have any type--there's no type checking till you try to use it. And print will take anything. For example,

def PrintTwice(item):
	print item
	print item

At this point, I'll steer you to the real Python tutorial. Click on the globe-question-mark tool, select "Main Python Documentation", then "Tutorial". You should probably skip to chapter 3--the earlier chapters are about non-Windows Python. Just remember, when they ask you to type something, do it at the ">>> " (or sometimes "... ") prompt in the Interactive Window.