I'm looking for the equivalent of Python decorators / Lisp macros / Java annotations (yes, I know that these are not necessarily equivalent themselves) in Actionscript. Tools that provide similar features would also be great (I'm using the Flex Builder plugin for Eclipse on Linux).
I'm writing a Flex application and here's what I want to accomplish:
I have encapsulated various sets of remote functionality in separate classes (this is sometimes called "Messaging Gateways" or "Remote Proxies"), where each method mirrors a method on the server, like so:
class UserManagementService extends MyHttpService {
//...
private final _urlBase:String = "http://example.com/services/users"
//...
public function usrGet(ix:int):User
{
url = urlBase + "/get";
mp:Dictionary = new Dictionary();
mp["ix"] = ix;
result:User = this._service.varSend(url, this.sEncodeParams(mp), Class("User"));
return result;
}
//...
}
Since I have the parameters and the return type of the remote function already in the function declaration, it would be nice to just add the URL suffix, like this (Python-inspired pseudocode):
#remotify("/get")
public function usrGet(ix:int):User { }
Now, wouldn't that be neat? ;-)
You can add what is called "metadata" in ActionScript like so:
[Remotify(prop="value")]
More information is here:
http://www.adobe.com/cfusion/communityengine/index.cfm?event=showdetails&productId=2&postId=11907
Related
here is the code of an alloy controller written in two different ways. Although the both work the same, Which one might be best practice?
example 1 of controller.js:
var currentState = true;
$.getState = function(){
return currentState;
}
example 2 of controller.js:
var currentState = true;
exports.getState = function(){
return currentState;
}
Titanium is based on the CommonJS framework. The exports variable is a special variable used typically to expose a public API in a class object. So when you want to expose a method of doSomething() on the MyModule.js class you would use the exports variable like this:
exports.doSomething() = function(args) {
//Some really cool method here
};
Then reference that class using
var myModule = require('MyModule');
myModule.doSomething();
However when referencing a view object the typical way to reference the is using the $. shortcut. You can see they prefer that method in the official documentation.
http://docs.appcelerator.com/platform/latest/#!/guide/Alloy_XML_Markup
The $ variable holds a reference to your controller instance. It also contains some references to all indexed views (understand, views for which you supplied an index in you xml markup).
Both ways are strictly equivalent as, during the compilation, Alloy will merge the content of the exports with your controller referenced in $. Adding them directly to the instance won't change a thing.
Neverthless, developers are used to see the public API as the set of functions exported via the special variable exports; Thus, I will recommend to keep using it in a clean and clear way (for instance, defining your functions in your module scope, and only expose them at the end or beginning of your controller).
function myFunction1 () { }
function myFunction2 () { }
function myFunction3 () { }
exports.myFunction1 = myFunction1;
exports.myFunction3 = myFunction3;
Thereby, your API is quite clear for people diving into your source code. (A readMe file is also highly recommended :) ).
I am loading an swf created in flash professional cs5 via the loader class into a flex 4.1 application. The flash file contains multiple movieclips that are exported for actionscript and those movieclips exist in many instances throughout the movie.
Iterating through everything, comparing class types seems to be the most easy but also the most redundant way to solve this. Is there any way of using the class name as a kind of global selector to access the clips?
I could also make the sub-clips in the flash listen for an event on which they perform an action, but I am not really sure what might be best.
In cases like these, I find that a good way to solve the problem is to create a statically accessable class that manages instances of other classes that are registered with it on instantiation. As an example...
public class GlobalStopper{
private static var clips:Array = [];
public static function add(mc:MovieClip):void{
clips.push(mc);
}
public static function stop():void{
var mc:MovieClip;
for(var i:int = 0, ilen:int = clips.length ; i < ilen ; i++){
mc = clips[i] as MovieClip;
if (mc) mc.stop();
}
}
}
and...
public class GloballyStoppableMovieClip extends MovieClip{
public function GloballyStoppableMovieClip(){
GlobalStopper.add(this);
}
}
Any and all instances of GloballyStoppableMovieClip are instantly registered with the GlobalStopper, so calling
GlobalStopper.stop();
...will stop all registered movieclips.
You can add in any other functions you want. Furthermore, instead of having add accept MovieClip instances, you could have it accept IStoppable or IPlayable objects that implement public functions stop() and play() that your movieclip subclass (or non-movieclip object that also might need to stop and play!) then implements.
But as for jQuery-like selectors? Not really the way I'd handle this particular issue.
i guess typing it out did the trick. i used the event solution:
in the root timeline i placed a function like this:
function cause():void {
dispatchEvent(new Event("do stuff",true));
}
and in the library clip's main timeline goes:
DisplayObject(root).addEventListener("do stuff", function (e:Event=null) {
... whatever ...
});
this is dirty but you get the idea.
I am just learning actionscript, so come across the problem
In my application I often call to different web services, and because I don't want to hardcode urls to them in my code, I am passing urls to the services as flashvars.
Currently I am doing it this way:
public var siteUrl:String;
public var gameId:String;
public function main():void
{
siteUrl = Application.application.parameters.siteurl;
gameId = Application.application.parameters.gameid;
Where main is a function, which is called on application's creation complete event.
This way I can call both variables from main file of the application but I want to access them from other files. (other as classes)
So is there a way to create class with constants and init values there with flashvars so I can use them everywhere (after importing of course)
The parameters are just stored in that Application.application.parameters object, and that's static. There's no reason you couldn't access that from other classes in your code.
If you want to write a class that wraps the parameters (maybe validates them or something) you could do that fairly easily. You can use a for each loop to loop over all the parameters. Something like:
var params:Object = Application.application.parameters
for(var name:String in params) {
var value:String = params[name] as String;
/* do something with the param */
}
If you want your class to actually verify things then it could just check for each parameter it expects and store it in a local variable.
It really just depends on your own preferences. Some people are fine with accessing the parameters object when they need it. Some people like having the extra code-completion by having a config class that actually defines all the expected config variables.
Update in response to comment:
Instead of having one module declare the variable and have other modules have to depend on that one to access the property it would be cleaner to have a single config module that everything that needs it would all use.
You could use a static class or singleton or some IoC stuff. Just for simplicity I'll show you a way you can do it with a static class.
class MyConfig {
private static var _infoService:String;
private static var _someOtherParam:int;
public static function get infoService():String { return _infoService; }
public static function get someOtherParam():int { return _someOtherParam; }
public static function initParams():Void {
var params:Object = Application.application.parameters;
_infoService = params.infoservice;
// just assuming you have a method to convert here. don't remember the
// code off the top of my head
_someOtherParam = convertToInt(params.someOtherParam);
}
}
Make sure when your app initializes it calls MyConfig.initParams(). You can have that method actually validate that it gets everything it expects and throw exceptions (or return an error) if there's a failure if you want.
Then wherever you need to use that config within your code you just import your config class and access the param. So getting infoService would just be:
var infoService:String = MyConfig.infoService;
Personally I wouldn't use a static class, but it was the easiest to show.
I'm using Python+PyAMF to talk back and forth with Flex clients, but I've run into a problem with the psudo-Enum-Singletons I'm using:
class Type {
public static const EMPTY:Type = new Type("empty");
public static const FULL:Type = new Type("full");
...
}
When I'm using locally created instances, everything is peachy:
if (someInstance.type == Type.EMPTY) { /* do things */ }
But, if 'someInstance' has come from the Python code, it's instance of 'type' obviously won't be either Type.EMPTY or Type.FULL.
So, what's the best way to make my code work?
Is there some way I can control AMF's deserialization, so when it loads a remote Type, the correct transformation will be called? Or should I just bite the bullet and compare Types using something other than ==? Or could I somehow trick the == type cohesion into doing what I want?
Edit: Alternately, does Flex's remoting suite provide any hooks which run after an instance has been deserialized, so I could perform a conversion then?
Random thought: Maybe you could create a member function on Type that will return the canonical version that matches it?
Something like:
class Type {
public static const EMPTY:Type = new Type("empty");
public static const FULL:Type = new Type("full");
...
// I'm assuming this is where that string passed
// in to the constructor goes, and that it's unique.
private var _typeName:String;
public function get canonical():Type {
switch(this._typeName) {
case "empty": return EMPTY;
case "full": return FULL;
/*...*/
}
}
}
As long as you know which values come from python you would just convert them initially:
var fromPython:Type = /*...*/
var t:Type = fromPython.canonical;
then use t after that.
If you can't tell when things come from python and when they're from AS3 then it would get pretty messy, but if you have an isolation layer between the AS and python code you could just make sure you do the conversion there.
It's not as clean as if you could control the deserialization, but as long as you've got a good isolation layer it should work.
I am using a Cairngorm MVC architecture for my current project.
I have several commands which use the same type of function that returns a value. I would like to have this function in one place, and reuse it, rather than duplicate the code in each command. What is the best way to do this?
Create a static class or static method in one of your Cairngorm classes.
class MyStatic
{
public static function myFunction(value:String):String
{
return "Returning " + value;
}
}
Then where you want to use your function:
import MyStatic;
var str:String = MyStatic.myFunction("test");
Another option is to create a top level function (a la "trace"). Check out this post I wrote here.
You have lots of options here -- publicly defined functions in your model or controller, such as:
var mySharedFunction:Function = function():void
{
trace("foo");
}
... static methods on new or existing classes, etc. Best practice probably depends on what the function needs to do, though. Can you elaborate?
Create an abstract base class for your commands and add your function in the protected scope. If you need to reuse it anywhere else, refactor it into a public static method on a utility class.