Flash MX 2004 Games : Art to ActionScript

Flash MX 2004 Games
up a name using a loop; we will look at using loops in Chapter 9. The format would be:
//Start loop with i=0, with each loop add 1 to the variable I
...
eval("Ball" + I)._x += 12;
...
You can even assign the value returned from the ‘eval’ function to another variable that then acts
as a reference to the original. For example:
1 var Arthur:Object = new Object();
2 Arthur.feet = 12;
3 Arthur.name = "Arthur";
4 var James:Object = new Object();
5 James.feet = 6;
6 James.name = "James";
7
8 var objRef = eval("Arthur");
9 trace(objRef.name + " has " + objRef.feet + " size feet");
10 objRef = eval("James");
11 trace(objRef.name + " has " + objRef.feet + " size feet");
Listing 7.10
Listing 7.10 gives an output of
Arthur has 12 size feet
James has 6 size feet
Lines 1 to 6 simply define and initialize to objects, one using the variable ‘Arthur’, the other
‘James’. Line 8 assigns a reference to the object called ‘Arthur’ to the variable called ‘objRef ’ using
the ‘eval’ function. This is then used for a trace action after which the value of ‘objRef ’ is changed
to be a reference to the object called ‘James’. Again a trace action is used to generate some output.
Although this is a very simple example and you may wonder when you will use it, movie clip
and object references are used extensively in game development.
Summary
We have covered a great deal in this chapter, from creating a basic variable to string slicing and
even user-defined classes. You have learnt how to add ActionScript to a frame action and even
to use code defined in a separate file. Along the way you have come across two of ActionScript’s
built-in objects: the string and the Math object. Now we want to move ahead by allowing our
programs to make simple decisions, and in the next chapter we will learn how.
100