awesome = "Scirra"[/code:3tbzidv8]
[code:3tbzidv8]ListBox.Add( awesome )[/code:3tbzidv8]
Right now what we'll notice happens is that the List box adds the line 'Scirra' when you press the button. This might seem pretty obvious, but for clarification, variables declared inside a script block are 'global' in that they are available to other scripts as well. This doesn't just include variables, it also includes classes and functions.

Okay lets have a look at how to declare a function!

<img src="http://dl.dropbox.com/u/939828/Tutorial/Script4.PNG">

[code:3tbzidv8]def MyFunction(param):
	return param + " without my pants"[/code:3tbzidv8]
Basically what we have done is declared a function 'MyFunction' which takes a single parameter called 'param'. Note that we dont declare the type of variable the function takes. It then returns the combination of whatever is in 'param' and the string " without my pants"

[code:3tbzidv8]ListBox.Add( MyFunction("scirra") )[/code:3tbzidv8]
Here we add a line to the list box. Instead of adding "scirra" or a variable, we call the function MyFunction("scirra"), telling python that we want to evalulate 'MyFunction' with param = "scirra". The result is it adds "scirra without my pants" to the list box

awesome = 10[/code:3o8cahs5]
This declares the variable 'awesome' as 10

[code:3o8cahs5]face = "hillarious"[/code:3o8cahs5]
This declares the variable 'face' as a string 'hillarious'

[code:3o8cahs5]
variable = 5
if variable == 5:
	Text.text = "cool"
[/code:3o8cahs5]
If you were to run this code, you would need to put a text object on the layout called 'Text'. But basically, if variable == 5 means:

[i]If the variable is equal to 5, run the code which is indented below'[/i]

Important things to notice is the indentation, the fact each 'instruction' is on a separate line, and that the if statement has a : at the end... also take note that python uses two equal signs for 'is equal to' like java and C++.

[code:3o8cahs5]for n in [1,2,3,4]:
	ListBox.Add(n)[/code:3o8cahs5]
To make this code work, you need to have a list box on the screen. Basically, for loops always loop over something. In C++ you might be familiar with writing: [i]for( int x = 0; x < 10; x++)[/i]...but python instead loops over all the elements in a set.

If you need to loop all the numbers from 0 to 100, its a waste of time to write [0,1,2,3,4,5.... so theres a handy function to remember - range:

[code:3o8cahs5]for n in range(0,10,2):
	ListBox.Add(n)[/code:3o8cahs5]

This will output 0, 2, 4, 6, 8 ... but not 10...so in C++ its the equivilent of writing:

[i]for (int n = 0; n < 10; n+= 2)[/i]

However, the python version is a bit shorter and probably easier to read! However it does take a bit of getting used to.

Sprite.X += 1[/code:2dnrrrmr]

When you run it, that sprite will move to the right 1 pixel per frame. Basically this script block of python is run each frame, just like events are. In fact, you can place a python script anywhere in the event sheet just like a regular event (ie. You can have a python script as a sub event)

Switch back to the layout editor, hold control and make a second instance of 'Sprite'. In fact, make a couple (press enter as you drag instead of constantly dragging and dropping) and now run the application.

You will notice only the first instance moves, none of the others do.

Python only evaluates one instance (in this case, the first).

If you want to move other instances, you need to refer to them in an array notation. Eg:

[code:2dnrrrmr]Sprite[0].X += 1;
Sprite[1].X += 1;[/code:2dnrrrmr]

Or...and this is a better way...take advantage of python for loop:

[code:2dnrrrmr]for s in Sprite:
	s.X += 1[/code:2dnrrrmr]

This means it will loop each instance of Sprite, and move it along the x axis by 1 unit per frame.