Actionscript 3, reading two files then triggering a function, best practice - actionscript-3

Question

I need to read a part of two files, and once both parts of both files are loaded to trigger a function that does some work.
What is the best way to approach this problem.
I am currently triggering the second file load once the first is loaded, however it seems poor coding style, I think this because my OO code starts looking procedural.
EDIT: So its an Air based app so using filestream.
In the end I found I actually needed to read each file in a different way. Because I need the same part of both files, and I dont know the file size, I need to read one file first and once I have fileStream.bytesAvailable and position, I can then look for the same data from the second file. I found I must handle files smaller than my read size and the end of files beyond multiples of my read size.

Answer 1

You don't specified what file and from where you wont to load the file but you can actually load multiples files in parallel.
If you want to read only part of file from local machine you can use AIR's FileStream class - very easy and you don't have to load whole few hundreds MB file:
import flash.filesystem.*;
var file:File = File.documentsDirectory;
file = file.resolvePath("Apollo Test/test.txt");
var fileStream:FileStream = new FileStream();
fileStream.open(file, FileMode.READ);
var str:String = fileStream.readMultiByte(file.size, File.systemCharset);
trace(str);
fileStream.close();
Another option is to use URLStream and listen for ProgressEvent.PROGRESSevents to read data of partially loaded file.
You may also want to see NetStream class which is used to stream video.

Answer 2

there is many options, using File, FileStream is only available on air applications.
The File class extends the FileReference class. The FileReference
class, which is available in Flash® Player as well as Adobe® AIR®,
represents a pointer to a file, but the File class adds properties and
methods that are not exposed in Flash Player (in a SWF running in a
browser), due to security considerations.
as noted above, if you are creating a non-AIR application, FileReference should be used instead of FileStream and File classes, as you dont tagged AIR in your question.
FileReference does not provide any open("path") to you (due to security considerations), but a browse method will be available and ask's your client's for selecting a file. here is an example, which also explain how to trigger a function when opening is done:
var filereference:FileReference = new FileReference();
filereference.addEventListener(Event.SELECT, onFileSelected);
var text_files:FileFilter = new FileFilter("Text Files","*.txt; *.html;*.htm;*.php");
var all_files:FileFilter = new FileFilter("All Files (*.*)","*.*");
filereference.browse([text_files, all_files]);
// triggered when a file is selected by user
function onFileSelected(e:Event):void {
filereference.removeEventListener(Event.SELECT, onFileSelected);
filereference.addEventListener(Event.COMPLETE, onFileLoaded);
filereference.load();
}
// triggered when file loading is complete
function onFileSelected(e:Event):void {
var data:ByteArray = fileReference["data"];
filereference.removeEventListener(Event.COMPLETE, onFileSelected);
}
two more events to be listened for suddenly error's occurred and displaying a progress bar for loading progress (its sync):
IOErrorEvent.IO_ERROR and ProgressEvent.PROGRESS