This doesn't change the value of 'myStuff.stuff', its value is still 'start' :
void main() {
Thing myStuff = Thing();
myStuff.stuff = 'start';
doStuff(myStuff);
print(myStuff.stuff);
}
void doStuff(Thing theStuff) {
theStuff = Thing();
theStuff.stuff = 'test';
}
class Thing {
String stuff = '';
}
How can I replace the referenced object in a function ?
You cannot do this in the method that you show. Dart is not pass by reference. It is pass by value.
If you want to be able to do something similar to this, you can either wrap your Thing object with a another object or provide a callback that modifies your original object.
Something along these lines for the wrapper class method:
void main() {
Thing myStuff = Thing();
myStuff.stuff = 'start';
ThingWrap wrapper = ThingWrap();
wrapper.thing = myStuff;
doStuff1(wrapper);
print(wrapper.thing.stuff);
}
void doStuff1(ThingWrap theStuff) {
var newStuff = Thing();
newStuff.stuff = 'test';
theStuff.thing = newStuff;
}
class Thing {
String stuff = '';
}
class ThingWrap {
Thing thing = Thing();
}
or the callback method:
void main() {
Thing myStuff = Thing();
myStuff.stuff = 'start';
doStuff1((newVal) {
myStuff = newVal;
});
print(myStuff.stuff);
}
void doStuff1(Function(Thing) callback) {
var newStuff = Thing();
newStuff.stuff = 'test';
callback(newStuff);
}
class Thing {
String stuff = '';
}
It's not immediately clear why you would want to do this based on the example you provided. If this were provided, it may have been possible to provide a cleaner solution. Simply providing a return value for doStuff and assigning it to myStuff in main would seem like the obvious way to do the same thing.
Related
class Foo {
public function bar():void { ... }
}
var clazz:Class = Foo;
// ...enter the function (no Foo literal here)
var fun:Function = clazz["bar"]; // PROBLEM: returns null
// later
fun.call(new Foo(), ...);
What is the correct way to do the above? The Java equivalent of what I want to do is:
Method m = Foo.class.getMethod("bar", ...);
m.invoke(new Foo(), ...);
Actual code (with workaround):
class SerClass {
public var className:String;
public var name:String;
private var ser:String = null;
private var unser:Function = null;
public function SerClass(clazz:Class):void {
var type:XML = describeType(clazz);
className = type.#name;
// determine name
name = type.factory.metadata.(#name=="CompactType").arg.(#key=="name").#value;
// find unserializer
var mdesc:XML = XML(type.method.metadata.(#name=="Unserialize")).parent();
if (mdesc is XML) {
unser = clazz[mdesc.#name];
}
// find serializer
var sdesc:XML = XML(type.factory.method.metadata.(#name=="Serialize")).parent();
if (sdesc is XML) {
ser = sdesc.#name;
}
}
public function serialize(obj:Object, ous:ByteArray):void {
if (ser == null) throw new Error(name + " is not serializable");
obj[ser](ous);
}
public function unserialize(ins:ByteArray):Object {
if (unser == null) throw new Error(name + " is not unserializable");
return unser.call(null, ins);
}
}
Here the function bar only exist when your class is instanciated :
var foo:Foo = new Foo()
var fun:Function = foo.bar // <-- here you can get the function from the new instance
if you want to access it directlty you have to make it static:
class Foo {
public static function bar():void{ ... }
}
now you can access your function from the class Foo:
var fun:Function = Foo.bar
or
var clazz:Class = Foo
var fun:Function = clazz["bar"]
I am not sure about what you are intending to do.
However AS3Commons, especially the reflect package have API's that let you work with methods, instances and properties of a class.
There are also API methods to create instances of certain class types on the fly and call their respective methods.
Cheers
It's not
fun.call(new Foo(), ...);
Use instead since no parameters are required for the function
fun.call(clazz);
The first parameter as specified by adobe docs.
An object that specifies the value of thisObject within the function body.
[EDIT]
Forgot to point out you have to instantiate a non-static class with the "new" keyword.
var clazz:Class = new Foo();
[EDIT2]
Ok I played around and think I got what you want.
base.as
package{
public class Base {
public function Base() {
trace('Base constructor')
}
public function someFunc( ){
trace('worked');
}
}
}
//called with
var b:Base = new Base( );// note I am not type casting to Class
var func:Function = b.someFunc;
func.call( );
My workaround is to store the function name instead of the Function object.
var fun:String = "bar";
// later...
new Foo()[fun](...);
I have this ObjectType class which is a class to help me do something like this:
object.type = ObjectType.TWO
//ObjectType.as
package
{
public class ObjectType
{
public static var ONE:String = "one";
public static var TWO:String = "two";
public static var THREE:String = "three";
public function ObjectType()
{
}
}
}
Let's suppose I'm creating a new class and I need a property named type. In that property set function I want to make sure that it's value is one of the ObjectType variables. How can I achieve this?
public function set type(value:String):void
{
for (var o:Object in ObjectType) {
if (value == o)
this._type = value;
} else {
//error
}
}
}
Not performance aware but without modifying anything you can use describeType function to check the static field and get the value back:
function valueInClass(clazz:Class, value:*):Boolean {
return describeType(clazz).variable.(clazz[#name.toString()] == value).length() != 0
}
public function set type(value:String):void
{
if (valueInClass(ObjectType, value)) {
this._type = value;
} else {
//error
}
}
I suppose the second code example you presented doesn't work...
I think it is because you're using the for in loop a little bit wrong.
for (var blah:String in somewhere){
// blah represents a KEY of the somewhere object
// to get the value of this key, use:
var theValue = somewhere[blah];
}
It's the for each loop that loops through the values. But for now I'll use the for in.
Also, it's not in ObjectType, but rather in the class' prototype, that is in ObjectType.prototype.
So, to fix this:
for (var o:* in ObjectType.prototype) {
if (value == ObjectType.prototype[o])
this._type = value;
} else {
//error
}
}
You can solve this using reflection.
A similar question was asked just a few days ago, you should be able to use the same solution, found here.
It should be noted that while the the accepted answer is right, it's also really slow. Not something that you want to do a lot. There are three simpler solutions.
One: Check the value itself:
public function set type(value:String):void
{
if( value != ObjectType.ONE && value != ObjectType.TWO && value != ObjectType.THREE )
return;
}
Obviously, the more constants you have the check the harder this becomes.
Two: Use ints as your constants
Change your ObjectType class to use ints:
public class ObjectType
{
public static var NONE:int = 0;
public static var ONE:int = 1;
public static var TWO:int = 2;
public static var THREE:int = 3;
public static var TOTAL:int = 4;
}
Notice the NONE and TOTAL in there? This makes it easy to check if your value is in the right range:
public function set type(value:int):void
{
if( value <= ObjectType.NONE || value >= ObjectType.TOTAL )
return;
}
You can add more values as needed and you just need to update TOTAL and it'll still work. This needs each value to be in order though.
Three: Use Enums
While Flash has no in-build class for enums, there's a lot of solutions available. Check our the Enum class from Scott Bilas: http://scottbilas.com/blog/ultimate-as3-fake-enums/
Using this as your base class your ObjectType class becomes:
public final class ObjectType extends Enum
{
{ initEnum( ObjectType ); } // static ctor
public static const ONE:ObjectType = new ObjectType;
public static const TWO:ObjectType = new ObjectType;
public static const THREE:ObjectType = new ObjectType;
}
And your check now becomes:
public function set type(value:ObjectType):void
{
...
}
Here, your setter now becomes type safe and will throw errors if anything other than an ObjectType is used.
It turns out that if using an ENUM type of check you should check for the constants property, not variables as showin in the example here:
ActionScript - Determine If Value is Class Constant
I am making a javaFX class and I need one of the variables to be initialized in order for it to work (in my program there's no default value I can use). This is the best I've come up with, but I'd like something that wont compile unless you initialize the variable.
Example Class:
Public class Class1{
public-init var var1:String;
postinit{
if(var1 == null){
println("You need to initialize var1");
}
}
I'd call it like this:
var object1 = Class1{var1:"input"};
How can I prevent it from compiling if I do this?
var object1 = Class1{};
Unfortunately, I think you have the best solution for forcing initialization. Only other thing you can do is set a default value:
public var var1: String = "BOGUS";
You can use this:
public class Class1 {
public var var1: String = "" on replace{
if (var1 == null) {
var1 = "";
}
};
}
var object1 = Class1{};
println(object1.var1);
object1.var1="HOLA :)";
println(object1.var1);
Output:
Mundo
HOLA
:)
Or maybe:
public class Class1 {
public-init var var1: String;
init {
if (var1 == null) { //or var1. length() == 0 ) {
println("You need to initialize var1");
Stage {
title: "Ups!!!"
onClose: function() {
}
scene: Scene {
content: [
Label {
text: "You need to initialize var1"
}
]
}
}
}
}
}
I am trying to understand the way the AsyncToken works in actionscript. How can I call a remote service and ensure that a specific parameter is available in the result or fault event functions? I think it is the async functionality I want to use.
The following code will hopefully explain what I am trying to do. Feel free to modify the code block as your explanation.
Thanks.
public function testSerivceCall(data:Object, callBackCommand:String):void
{
// Assume callBackCommand == "FOO";
// How can I pass in callBackCommand as a parameter to the result or fault events?
// How do I create an async token here?
var remoteObject:RemoteObject;
remoteObject = new RemoteObject();
remoteObject.destination = "zend";
remoteObject.source = "MyService";
remoteObject.endpoint = "http://example.com/service";
remoteObject.test.addEventListener(ResultEvent.RESULT, _handleTestResult);
remoteObject.test.addEventListener(FaultEvent.FAULT, _handleTestFault);
remoteObject.test(data);
}
private function _handleTestResult( event:ResultEvent ) : void
{
// How do I get the async token value?
// How can I get the value of callBackCommand in this code block?
if (callBackCommand == "FOO")
{
// do something related to "FOO"
}
else
{
// do something else with the result event
}
}
private function _handleTestFault( event:FaultEvent ) : void
{
// How do I get the async token value?
// How can I get the value of callBackCommand in this code block?
}
An edit to make this question more clear:
Assume I make the following method call somewhere in my code:
testSerivceCall(personObject, "LoginCommand");
How do I get access to the actual string "LoginCommand" inside the _handleTestResult function block?
The reason I want to do this is because I want to dynamically call back certain functions and hand off the result data to specific commands that I know ahead of time when I am making the service call.
I am just having a time grokking the AsyncToken syntax and functionality.
I did not even need closures. I added a class as below which I called externally.
The call was like this:
public class MyClass
{
...
var adminServerRO:AdminServerRO = new AdminServerRO();
adminServerRO.testSerivceCall("FOO",cptyId);
}
public class AdminServerRO
{
private function extResult( event:ResultEvent, token:Object ) : void
{
//the token is now accessed from the paremeter
var tmp:String = "in here";
}
private function extFault( event:FaultEvent ) : void
{
var tmp:String = "in here";
}
public function testSerivceCall(callBackCommand:String, cptyId:String):void
{
var remoteObject:RemoteObject = new RemoteObject();
remoteObject.destination = "adminServer";
var token:AsyncToken = remoteObject.getCounterpartyLimitMonitorItemNode(cptyId);
token.addResponder(new AsyncResponder(extResult,extFault,cptyId));
}
}
While the accepted answer will accomplish what the original submitter wants it does not actually answer the question which was asked. An AsyncToken is created as a result of a remote method call and is accessible from the ResultEvent. Since AsyncToken is a dynamic class you can add whatever property to it that you want. The code below should demonstrate this:
public function testSerivceCall(data:Object, callBackCommand:String):void
{
var remoteObject:RemoteObject;
remoteObject = new RemoteObject();
remoteObject.destination = "zend";
remoteObject.source = "MyService";
remoteObject.endpoint = "http://example.com/service";
remoteObject.test.addEventListener(ResultEvent.RESULT, _handleTestResult);
remoteObject.test.addEventListener(FaultEvent.FAULT, _handleTestFault);
var token:AsyncToken = remoteObject.test(data);
token.callBackCommand = callBackCommand;
}
private function _handleTestResult( event:ResultEvent ) : void
{
if (event.token.callBackCommand == "FOO")
{
// do something related to "FOO"
}
else
{
// do something else with the result event
}
}
private function _handleTestFault( event:FaultEvent ) : void
{
//event.token.callBackCommand should be populated here too
}
If you want to access the properties used during the remote call (parameters to the call and/or AsycToken), you can make use of closures. Just define the result event handler inside the calling method as a closure. It can then access any variable in the calling function.
public function testSerivceCall(data:Object, callBackCommand:String):void
{
var _handleTestResult:Function = function( event:ResultEvent ) : void
{
// token is visible here now
if (callBackCommand == "FOO")
{
// do something related to "FOO"
}
else
{
// do something else with the result event
}
}
var remoteObject:RemoteObject;
remoteObject = new RemoteObject();
remoteObject.destination = "zend";
remoteObject.source = "MyService";
remoteObject.endpoint = "http://example.com/service";
remoteObject.test.addEventListener(ResultEvent.RESULT, _handleTestResult);
remoteObject.test.addEventListener(FaultEvent.FAULT, _handleTestFault);
var token = remoteObject.test(data);
}
If I'm reading your question correctly, you're trying to figure out how to access the actual data returned by the ResultEvent ?
If so, assuming you've made the call correctly and you've gotten data back in a format you're expecting:
private function _handleTestResult( event:ResultEvent ) : void
{
// you get the result from the result property on the event object
// edit: assuming the class Person exists with a property called name
// which has the value "John"
var person : Person = event.result as Person;
if (person.name == "John")
{
Alert.show("John: " + person.name);
}
else
{
Alert.show("Not John: " + person.name);
}
}
private function _handleTestFault( event:FaultEvent ) : void
{
// Maybe you know the type of the returned fault
var expectedFault : Object = event.fault as MyPredefinedType
if (expectedFault.myPredefinedTypesPredefinedMethod() == "BAR")
{
// something here
}
}
The ResultEvent has a property called result which will hold an instance of the object returned by the result (it might be the output of an XML file if using a web service, or a serialized object if using AMF, for example). This is what you want to access. Similarly, FaultEvent has a fault property that returns the fault information.
Edit: Changed code in _handleTestResult() in response to Gordon Potter's comment.
I'm developing a flash (Flash 9, AS3) to connect to a server and send/receive/parse data to a chat on JavaScript/HTML.
I have a structure like this:
package {
public class myClass {
String.prototype.escapeHtml = function() {
var str = this.replace(/&/g, "&");
str = str.replace(/</g, "<");
str = str.replace(/>/g, ">");
return str;
}
function writeToBrowser(str:String) {
ExternalInterface.call("textWrite",str.escapeHtml());
}
}
}
When I compile it, I get this error:
1061: Call to a possibly undefined
method escapeHtml through a reference
with static type String.
If I remove the :String, it all works fine, but then I'd have to check if str is a String and if it's not undefined and so on.
I have many functions like this on my code, many of them receive user-entered data, so I think that removing the :String and doing many checks on every function isn't the best approach.
How can I make this right?
Then just define the function:
public function escapeHtml( str : String ) : String
{
var str = this.replace(/&/g, "&");
str = str.replace(/</g, "<");
str = str.replace(/>/g, ">");
return str;
}
in your class.
And call it:
public function writeToBrowser( str : String )
{
ExternalInterface.call( "textWrite", escapeHtml( str ) );
}
:)
you get an error because the compiler is in strict mode.
if you want to stay in strict mode you can try this:
ExternalInterface.call("textWrite",str["escapeHtml"]() );
Prototype is actually legacy.
You should extend the String class and use your custom class
package {
public class myClass {
public function writeToBrowser(str:CustomString) {
ExternalInterface.call("textWrite",str.escapeHtml());
}
}
public class CustomString {
public function escapeHtml():String {
var str = this.replace(/&/g, "&");
str = str.replace(/</g, "<");
str = str.replace(/>/g, ">");
return str;
}
}
}