i want make own flex library and in this library use own actionscript file which will i use in more component in this library..this file contents eg only code
public function computeSum(a:Number, b:Number):Number {
return a + b;
}
but when i can this create just when i click File-New-Actionscript File (filename - OK) is in Problem view Error: A file found in a source-path must have an externally visible definition. If a definition in the file is meant to be externally visible, please put the definition in a package
thanks for help
You should encapsulate it on class, in order to use it with import directive, else u could use it with include
Another approach is to create a "helper" class, or so called "singleton" class.
- a class having only 1 instance, created statically.
on this class u can expose the library functions which u do need and use them everywhere.
package
{
public class Singleton
{
private static var singleton : Singleton
public static function getInstance() : Singleton
{
if ( singleton == null )
singleton = new Singleton();
return singleton;
}
public function Singleton()
{
}
public function visibleTroughtTheSingletonfunction( arg1 : int ... ) : void
{
}
public static function directlyVisiable() : void
{
}
}
}
the accessing the singleton would be something like :
Singleton.getInstance.visibleTroughtTheSingletonfunction( 1 );
OR
Singleton.directlyVisiable();
depending on your needs.
Well first you'll need to create a class (and a package) and put that method inside that (not just into an empty AS file) and second if you want to be able to access the method without creating an instance of the class make this method static.
If you don't need to change the class file during runtime then make action class compile into swc library.
create a Action script project and compile it in the bin folder you found the .swc library file. include that .swc into your project .
Related
I created a website and would like to have a class to centralize all the code that I use frequently in the entire project, for instance, a method to connect to the database. Question: after I create this class, on the App_Code folder, how can I use it in the aspx.cs pages? I mean, should a reference it? Should I inform add a namespace?
Thanks!
Create the class file as public and you will be able to access the class file at any part of your project.
namespace applicationName
{
public class DataManager
{
public static DataTable GetData(StringBuilder sql)
{
}
}
}
you can access the DataManager from your code.
DataManager.GetData(SQL);
Yes, put your class in a namespace and consider making the class static if possible, that way it can be used in code throughout your project without instantiating the class. This is common for utility classes that pass in objects and do work with them, but do not need the actual utility method to be part of a class instance.
For example:
namespace My.Utilities
{
public class static ConnectionStringHelper
{
public static string GetConnectionString()
{
// Logic here to actually get connection string
return yourConnectionString;
}
}
}
Now, code in your project just needs to reference the My.Utilities namespace and then can use the GetConnectionString() method, like this:
using My.Utilities;
string connString = ConnectionStringHelper.GetConnectionString();
You can do it a number of ways. Technically you can drop the namespace completely and your code becomes a free for all (accessible from anywhere naturally). I prefer to use namespaces personally, but I have seem people just avoid them.
If your class Foo is in Some.Namespace, you can reference it as such:
Way one:
Some.Namespace.Foo foo = new Some.Namespace.Foo()
Way two: Use the "Use" command
If your class is inside of Some.Namespace and you don't want all the junk preceding your class name, you can add:
using Some.Namespace;
to the top of your file.
I may be miss understanding what you are saying. If you are talking about setup, you can make a centralized class that manages everything. This class can be a singliton. For instance:
class MyClass
{
public static MyClas Singliton;
static MyClass()
{
Singliton = new MyClass();
}
public void someFunction()
{
}
}
This will create and manage a single reference to your class so that everything is managed out of there (hence being called a "singleton"). As a result, you can access it by:
MyClass.Singliton.someFunction();
There are ways to protect your singliton instance from being overwritten, but this is the basic idea. If you want to manage stuff out of a single location without recreating classes, singletons are the way!
http://msdn.microsoft.com/en-us/library/ff650316.aspx
If the class is wrapped in a namespace, then yes, you'll need a using statement that matches your namespace. For instance, if your class is wrapped in a namespace like so:
namespace My.Namespace
{
public class Foo
{
//Methods, properties, etc.
}
}
then anywhere you want to use that class you'll need to add
using My.Namespace;
to the top of the files where you want to utilize the class(es) you've defined. Then you can use your class as you would expect:
Foo foo = new Foo(); //for a new instance
Foo.Bar(); //for a static method
This is, of course, assuming that the class is in the same assembly and you don't want to mess with adding it to the GAC.
Alternatively, if for some reason you don't to use a using statement you can use the fully qualified name of the class:
My.Namespace.Foo foo = new My.Namespace.Foo(); //for a new instance
My.Namespace.Foo.Bar(); //for a static method
This is most useful if you have namespaces that conflict, for instance if you had
namespace My.Namespace
{
public class Foo
{
//Methods, properties, etc.
}
}
somewhere, and
namespace MyOther.Namespace
{
public class Foo
{
//Methods, properties, etc.
}
}
somewhere else, but needed to use them both in the same scope.
I've got an object declared and instantiated in my Flex application's singular MXML file:
public var CDN:CDNClass = new CDNClass;
I would like to access this same CDN object (and its public methods and properties) in another class declared in a separate .as file as such:
package my.vp
{
import my.media.CDNClass;
public class SyncConnectorManager
{
private function syncMessageReceived(p_evt:SyncSwfEvent):void
{
switch (p_evt.data.msgNm)
{
case "startStream" :
// Play a stream
CDN.parsePlayList(p_evt.data.msgVal);
break;
But when I try to access the public method parsePlayList in the CDN object in a method in the class defined in the .as file, I get the following error:
Access of undefined property CDN
The reason I want to do this is to break up the logic of my application into multiple AS files and have minimal MXML files, probably only one.
Thanks - any help is much appreciated. Perhaps my OOD/OOP thinking is not correct here?
IT depends on your class architecture. For your code to work, the CDNClass instance must be defined and implemented inside your SyncConnectorManager.
Generally, you can always call down into components, but should never call up
One option is to pass the instance ofCDNClass to a variable inside SyncConnectorManager. Add this variable to your SyncConnectionManager class:
public var CDN:CDNClass = new CDNClass;
And at some point do this:
syncConnectorManagerInstance.CDN = CDN;
That way both classes will have access to the same CDN instance and can call methods on it.
Yes, your OOP thinking is not correct here. You should take in mind differences between classes and instances. This line declares a filed in a current class and initiates it with an instance:
public var CDN:CDNClass = new CDNClass;
So current instance of your MXML class (you can think about it as usual AS class with some other notation) has public field. To operate with CDN instance you need something from the following:
Read the value of CDN (as far as it is public) from the instance of your MXML class. You need some reference to it for that.
The instance of your MXML class can have a reference to the instance of SyncConnectorManager and SyncConnectorManager should have a way to inject the value of CDN there. Something like:
Your class:
package my.vp
{
import my.media.CDNClass;
public class SyncConnectorManager
{
private var CDN:CDNClass;
public function SyncConnectorManager(CDN:CDNClass)
{
this.CDN = CDN;
}
private function syncMessageReceived(p_evt:SyncSwfEvent):void
{
switch (p_evt.data.msgNm)
{
case "startStream" :
// Play a stream
CDN.parsePlayList(p_evt.data.msgVal);
break;
In your case SyncConnectorManager class hasn't CDN declared (the problem of the compiler error you mentioned) and instantiated (the problem of NPE even if you just declare field).
As the bottom line I can suggest you to follow ActionScript naming and coding conventions to talk other people and team members about your code :)
Suppose I have the following simple wrapper of a NativeClassInstance.
public ref class Wrapper
{
private:
NativeClass *_wrapped;
public:
Renderer()
{
_wrapped = new NativeClass();
}
~Renderer()
{
delete _wrapped;
}
operator NativeClass*()
{
return _wrapped;
}
}
Now, I want to create an instance of Wrapper from C# with Wrapper wrapper = new Wrapper() and use it in another native functionalities wrapper that resides in another assembly with Helper.Foo(wrapper) (nothing strange having other functionalities not directly related to the wrapped classes in another assembly, IMO):
// Utilities is in another Assembly
public ref class Helper
{
public:
static Foo(Wrapper ^wrapper)
{
// Do something in native code with wrapper->_wrapped
}
}
The results with the implicit user conversion is:
candidate function(s) not accessible
If I make _wrapped public it is:
cannot access private member declared in class ...
Now, I've learnt that native type visibility is private outside of the assembly. So, how I'm supposed to use the wrapped entity in native code outside the assembly it's defined? I've read of make_public but you can't use with template types so it seems very limiting in the general case. Am I missing something? Is there a more correct solution?
I haven't been able to successfully expose native types using make_public, however a solution I have used is to put NativeClass in its own native DLL and then a) reference the native DLL from both assemblies; and b) pass the pointer to the native class around as an IntPtr.
Under the above scenario, instead of having an operator NativeClass* you might use a property such as
property IntPtr WrappedObject {
IntPtr get() { return IntPtr(_wrapped); }
}
You then retrieve NativeObject in you helper assembly by
static void Foo(Wrapper ^wrapper)
{
NativeObject *_wrapped
= static_cast<NativeObject*>(wrapper->WrappedObject.ToPointer());
// ... do something ...
}
If you use make_public, your solution of making _wrapped public should work (it would obviously be best to make a public accessor instead). Regarding your comment "I've read of make_public but you can't use with template types so it seems very limiting in the general case." I agree--read here for the workaround I used:
http://social.msdn.microsoft.com/Forums/en-US/vclanguage/thread/b43cca63-b0bf-451e-b8fe-74e9c618b8c4/
More related info:
Best workaround for compiler error C2158: make_public does not support native template types
Good luck!
I have a doubt,.... How would you create a Singleton class in Flex...
Is there any convention like the class name should eb Singleton or it should extend any other class.
How many Singleton class can a project have?
Can anyone say the real time usage of a Singleton class?
I am planning to keep my components label texts in a Singleton class... Is it a good approach.
Can of worms asking about singletons!
There are a few different options about creating singletons mainly due to AS3 not having private constructors. Here's the pattern we use.
package com.foo.bar {
public class Blah {
private static var instance : Blah;
public function Blah( enforcer : SingletonEnforcer ) {}
public static function getInstance() : Blah {
if (!instance) {
instance = new Blah( new SingletonEnforcer() );
}
return instance;
}
...
}
}
class SingletonEnforcer{}
Note that the SingletonEnforcer class is internal so can only be used by the Blah class (effectively). No-one can directly instantiate the class, they have to go through the getInstance() function.
hope I'm not hitting dead horses here :)
(edit: ahh, I'm just repeating phils link)
Gregors singleton implementation does not protect against invoking the constructor with a null value, as in:
var b:Blah = new Blah(null);
You will still have only 1 instance, but invoking the constructor is still possible with the consequences that follows.
If you absolutely must enforce the singleton, the constructor should make sure that the enforcer parameter isn't null.
public function Blah( enforcer : SingletonEnforcer ) {
if(!enforcer){
throw new Error("whoops!");
}
}
You should also be concerned about ApplicationDomain when loading swf files. External swf files that uses the same definitions, may have multiple singleton instances (1 in each separate applicationdomain) if you do not specify that the swf file must be loaded into the existing applicationdomain.
This means that Blah.getInstance() in AAA.swf is not the same instance as Blah.getinstance() in BBB.swf, if AAA.swf loads BBB.swf without a LoaderContext instance that tells the plugin to load BBB.swf into the same ApplicationDomain as AAA.swf
First you can reference a previous question to find out how to create a singleton class. You can find more info from a Yakov Fain presentation as well.
Second question, your project can technology have as may singleton class as you see fit but it will only create 1 instance of each. For example, in the cairngorm architecture you have 3 main singletons: controller, service and model. The number of actual class can very depending on your project.
Finally, A real world solutions would be. You have 2 components that need to talk to each other but you don't want them to know the other exists. Meaning sometimes the components are there and sometimes they are not...so you need them to be loosely coupled. you can uses singletons to pass the data from one component to the other with out "talking" to them directly.
Using singletons is a good approach if you need to pass data around your application from component to component and would like to decouple them from each other.
package com.foo.bar
{
public class MySingleton
{
private static var _instance:MySingleton = new MySingleton;
private var _myName:String;
public static function get instance():MySingleton
{
return _instance;
}
public function set myName(value:String):void
{
_myName = value;
}
public function get myName():String
{
return _myName;
}
}
}
Notice the absence of a constructor here.
Hello you could check out the following of a Flex Singleton Class example on http://www.how-to-code.com/flex/flex-design-patterns/flex-singleton-class.html
I'm trying to implement a plugin system for our application, and having a devil of a time getting SWF file which was dynamically loaded itself, load additional SWF files.
It goes something like this:
Main Application Shell loads...
---------+ Application loads...
-----------------+Plugin(s)
I have no problem getting app #1 to load app #2
However, try as I might, I cannot get app #2 to load and instantiate #3
I've tried various permutations using the ModuleManager, but this is the closest I get. When the onLoadComplete method get invoked, I can see that the SWF loaded, however the factory always returns NULL.
What is interesting is that when I extract this out in its own application, it works fine. This issue is triggered by the fact that I'm loading Plugin from a SWF that was loaded dynamically itself.
I believe this is due to the ApplicationDomain, but I cannot make heads or tails of it. I tried specifying currentDomain, new ApplicationDomain(Application.currentDomain) and new ApplicationDomain() without success.
Also, it is important to note that I cannot make reference a hard reference to the Foo class in either applications since by their nature, we will not know ahead of time what they will contain.
Googlin' around, this seems to be a fairly known problem, but I have not found a (clear) solution yet.
.
.
.
assetModule = ModuleManager.getModule("Foo.swf");
assetModule.addEventListener(ModuleEvent.READY, onLoadComplete );
assetModule.addEventListener(ModuleEvent.ERROR, onLoadError);
assetModule.load();
.
.
.
private var _pluginInstance:Plugin;
private function onLoadComplete( event:Event ):void
{
trace("module loaded");
_pluginInstance = assetModule.factory.create() as Plugin;
if( _pluginInstance )
_pluginInstance.startup();
else
Alert.show("unable to instantiate module");
}
private function onLoadError( event:Event ):void
{
Alert.show("error");
}
My Plugin looks like this:
package
{
import mx.collections.ArrayCollection;
import mx.modules.ModuleBase;
public class Plugin extends ModuleBase
public function startup():void
{
}
.
.
.
}
and
package
{
import Plugin;
import mx.modules.ModuleBase;
public class Foo extends Plugin
{
public function Foo()
{
trace("foo constructor invoked");
}
override public function startup():void
{
trace("foo started");
}
.
.
.
}
# joshtynjala is right. I found try just using Object then calling methods on it (don't cast).
var MyPlugin : Object = getPlugin();
MyPlugin.doPluginFunc();
Generally can cast between system/flex classes no problem. Don't know if putting Plugin as a runtime library would help ?
If you really want to use a common interface between your plugin and your application, your application's Plugin class must be the same as your plugin's Plugin class. To do so, they need b to be in the same ApplicationDomain.
//In an external library
public interface Plugin {}
//In your application
_pluginInstance = assetModule.factory.create() as Plugin;
...
//In your plugin
public class MyPlugin implements Plugin
The problem is, when you will compile your plugin swf, you will also compile Plugin. This is not a problem, but you need to tell your application that it's the same as his :
var loader:Loader = new Loader();
loader.addEventListener(Event.COMPLETE, onLoadComplete);
loader.load(new URLRequest("plugin.swf"), new LoaderContext(false, ApplicationDomain.currentDomain));
ApplicationDomain.currentDomain is the key here. If you refer to the docs :
Loader's own ApplicationDomain. You
use this application domain when using
ApplicationDomain.currentDomain. When
the load is complete, parent and child
can use each other's classes directly.
If the child attempts to define a
class with the same name as a class
already defined by the parent, the
parent class is used and the child
class is ignored.