Running-order of nested function-calls delayed/altered due to URLloader in AS3? - actionscript-3

Question

First of all: English is not my first language. ;-)
I am compiling the following code:
var sqldata:String;
function sql(saveorload,sqlstring) {
var sqlloader = new URLLoader();
var sqlrequest = new URLRequest("http://***/sql.php");
sqlrequest.method = URLRequestMethod.POST;
sqlloader.addEventListener(Event.COMPLETE, sqldonetrace);
var variables:URLVariables = new URLVariables();
variables.sqlm = saveorload;
variables.sqlq = sqlstring;
sqlrequest.data = variables;
sqlloader.load(sqlrequest);
}
function sqldonetrace(e:Event) {
sqldata = e.target.data;
}
sql("1","SELECT * FROM songs WHERE `flag2` LIKE '0'");
trace (sqldata);
So, here comes the problem:
"sqldata" is traced as "null". AS3 seems to run "sql", then "trace" and then "sqldone", but i would need sql -> sqldone -> trace...
I can't put the trace-command in the sqldone-function because it is stored as *.as and loaded at different points in my .swf and not always followed by only a trace-command.
Any Ideas/hints/flaws in script?

Answer 1

Actionscript is, by design, an event driven language. It also guarantees that the code executes in a single thread i.e. if a function call starts, no other(new call) actionscript code would execute until the first call finishes.
That being said, what you should have is to pass a complete handler to sql(...).
function sql(saveorload:String, sqlstring:String, completeHandler:Function):void
{
var sqlloader = new URLLoader();
var sqlrequest = new URLRequest("http://***/sql.php");
sqlrequest.method = URLRequestMethod.POST;
sqlloader.addEventListener(Event.COMPLETE, completeHandler);//tell urlloader to use the complete handler passed in parameters
var variables:URLVariables = new URLVariables();
variables.sqlm = saveorload;
variables.sqlq = sqlstring;
sqlrequest.data = variables;
sqlloader.load(sqlrequest);
}
And then use it from some other place like:
sql("1","SELECT * FROM songs WHERE `flag2` LIKE '0'", sqldonetrace);
function sqldonetrace(e:Event)
{
var sqldata:String = e.target.data;
trace (sqldata);
}
Also, I think you should check for error events from urlloader. Pass another parameter to sql as errorHandler