Problems with casting or string (literals?), and dynamic references

[pixel_streamer]

Can someone please tell me the difference in these three code chunks?

1) is it casting a string, or incorrect syntax?

2) this works,

3) if #2 works as a plain "" string, then what cases would prompt the string to need String("whatever") ?

if menu_item_txt is a textField at _level0:

1)


for (var i = 0; i < 7; i++) {
var myText:Object = this[String(menu_item_txt) + i];
//trace(myText);
myText.autoSize = true;
myText.embedFonts = true;
myText.antiAliasType = "advanced";
myText.gridFitType = "subpixel";
myText.thickness = 0;
myText.sharpness = 45;
}
2)


for (var i = 0; i < 7; i++) {
var myText:Object = this["menu_item_txt" + i];
//trace(myText);
myText.autoSize = true;
myText.embedFonts = true;
myText.antiAliasType = "advanced";
myText.gridFitType = "subpixel";
myText.thickness = 0;
myText.sharpness = 45;
}
3)


for (var i = 0; i < 7; i++) {
var myText:Object = this[String("menu_item_txt") + i];
//trace(myText);
myText.autoSize = true;
myText.embedFonts = true;
myText.antiAliasType = "advanced";
myText.gridFitType = "subpixel";
myText.thickness = 0;
myText.sharpness = 45;
}