Flash MX 2004 Games : Art to ActionScript

Chapter 7: So what is a variable?
But, what if you do not know the name of the object until the player clicks on a button? By
clicking on the button the user can set the value of a variable you have created called charName,
to ‘Arthur’. Now ‘Arthur’ is a string that is stored in the variable charName. So how do you use
the charName to access the value of feet in the object called Arthur? If you use
charName.feet;
this does not access the object; instead it accesses the string called charName. This does not have
a feet setting so Flash would return zero or, with strict data typing, an error.
1 var Arthur:Object = new Object();
2 Arthur.feet = 12;
3 var charName:String = "Arthur";
4 trace(charName.feet);
Listing 7.9
The program shown in Listing 7.9 would result in the error message shown in Figure 7.9.
Figure 7.9 Output from Listing 7.9
Instead you want to get at the object named ‘Arthur’. This is achieved with the ‘eval’ keyword:
eval("charName").feet;
The function eval takes a string parameter and returns a variable or object with that name
if it exists. The eval function can also be very useful for accessing movie clip instances
when you have many copies of a movie clip all with names that include a number: Ball0,
Ball1 ... Ball12. If you want to apply the same code to each instance then you would build
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