In the Package constructor I added the event handler for OnStartupComplete event. But when I run the code, the the event handler is not called. What am I doing wrong?
There's a bug in VS that recycles the DTEEvents object (with your event handlers) unless you keep an explicit reference to it. You need something like this:
[ProvideAutoLoad(VSConstants.UICONTEXT.NoSolution_string)]
[ProvideAutoLoad(VSConstants.UICONTEXT.SolutionExists_string)]
class MyPackage : Package
{
DTEEvents _EventsObj;
protected override void Initialize()
{
var dte = (EnvDTE.DTE)GetService(typeof(EnvDTE.DTE));
_EventsObj = dte.Events.DTEEvents;
_EventsObj.OnStartupComplete += OnStartupComplete;
}
void OnStartupComplete()
{
}
}
Try moving your code from package constructor to the Initialize() method of the package. It should help, but if it doesn't, test some other UICONTEXT_??? values for your AutoLoad attribute, maybe UICONTEXT_NoSolution ?
See my answer here: http://social.msdn.microsoft.com/Forums/en-US/vsx/thread/eb1e8fd1-32ad-498c-98e9-25ee3da71004
I believe that it is because you could be boxing and unboxing your DTE object before doing the event subscription. This is a huge nuisance, and quite surprising that the DTE object cant be passed around easily through service location for the purpose of event subscriptions; but this seems to be the culprit.
I had tried to keep a reference to the DTE object but it made no difference as I was doing that anyway. Some events will work, and some won't; but this is consistent.
Related
I use a unit of work pattern a lot in my flex projects. I'll have a class that might call a web service, put the data in a sqlite db, refresh a model with the data then raise an event.
I usually call these inline and pass in some singleton classes:
protected function CareerSynced():void
{
var process:ProcessWorkouts = new ProcessWorkouts(_dataModel, _trainerModel, _databaseCache, _database.Conn);
process.addEventListener("AllWorkoutsProcessed", AllWorkoutsProcessed);
process.UpdateAllUnprocessed();
}
I'll then get the response like this:
private function AllWorkoutsProcessed(event:DataReceivedEvent):void
{
//do something here
}
My question is, am I adding that event listener correctly? I think I might be causing a memory leak, but I'm not sure. I've also thought about using a weak reference. I'm confused about when to use them. Would this be one of those cases?
Should it be like this?
process.addEventListener("AllWorkoutsProcessed", AllWorkoutsProcessed,false, 0, true);
I would either go with the weak reference or just remove the listener:
private function AllWorkoutsProcessed(event:DataReceivedEvent):void
{
event.target.removeEventListener("AllWorksoutsProcessed",AllWorkoutsProcessed);
}
I could list out my reasons but I'll just point you to this.
I am working on a Silverlight application using V3 SP1 of MVVM Light Toolkit.
My application is fully French/English. All UI elements (buttons, labels, etc.) and all the data (models). I need dynamic language switching and this is fully implemented and works with anything coming from a resource file. What I am struggling with is the ViewModels.
The Models have language specific prperties (DescriptionEn, DescriptionFr) and an additional property call LocalizedDescription which uses the current culture to return call the language specific property.
When the language changes (via a button click) I raise and broadcast (via the Messenger) a property changed event.
In each of my ViewModels, I register to receive the property changed message for the language swap.
I want to notify all the properties of the ViewModel that something has changed.
From: http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged.propertychanged.aspx
The PropertyChanged event can indicate all properties on the object have changed by using either null or String.Empty as the property name in the PropertyChangedEventArgs.
However, since the toolkit abstracts the raising of the changed event with RaisePropertyChanged(...) I cannot get this to work. I have also examined the source of the tookit and discovered that RaisePropertyChanged calls VerifyPropertyName(..) which in turn returns an error is the property does not belong to the ViewModel. I also noticed that the VerifyPropertyName method is attributed with Conditional("DEBUG"), but even if I choose the Release configuration, the ArgumentException("Property not found") is still raised.
Does anyone know of a way to get this to work using the toolkit aside from manually calling RaisePropertyChanged for every property of the ViewModel?
Follow-up:
Based on the comment from Simon, I attempted to create my own class that extends ViewModelBase. I looked at the source on CodePlex and decided to create a single method called RaiseAllPropertyChanged(). It would simply be a copy of the RaisePropertyChanged(string propertyName) but without the parameter and without the call to VerifyPropertyName(...). I cannot get it to work. Here is what I have.
public class ViewModelBaseExtended : ViewModelBase
{
protected void RaiseAllPropertyChanged()
{
var handler = this.PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(String.Empty));
}
}
}
But I get a compiler error: The event 'GalaSoft.MvvmLight.ViewModelBase.PropertyChanged' can only appear on the left hand side of += or -=. This is a copy of the code that is used in the ViewModelBase.
Can someone offer some advice as to how to get this to work?
Solution:
I copied all the code from ViewModelBase into a new class. I then added the method RaisePropertyChanged() mentioned above which instantiates the PropertyChangedEventArgs class with String.Empty. This is now the new subclass for my ViewModels.
Thanks again to Simon for leading the way!
In case you're reading this in 2016, you can use ObservableObject and notify that all of the properties have changed by doing:
RaisePropertyChanged(string.Empty);
Unfortunately this is not possible with the current code-base of MVVMLight
In the short term your have 2 options:
User your own custom base class. And by custom base class I mean "Do not inherit from the MVVMLight class".
Download and compile MVVMLight in Release mode. This will force the "VerifyPropertyName" method to be excluded. Of course then you don't get the value of property name checks.
I am sure Laurent Bugnion will have this fixed soon.
A lighter solution to this problem would have been to override RaisePropertyChanged(string propertyName) in your class :
protected override void RaisePropertyChanged(string propertyName)
{
if (propertyName != null)
{
base.RaisePropertyChanged(propertyName);
}
else
{
var handler = PropertyChangedHandler;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(null));
}
}
}
I am trying to dispatch a custom event from one flex module to another.
The code which dispatch the event is as below
Application.application.Destination.child.dispatchEvent(
new AlgoEvent(AlgoEvent.GETFROMPARENT_LOCAL_EVENT));
here AlgoEvent is a custom event
on the other side the module which catches and handles the event has this code:
public function sendParametersToChild(e:AlgoEvent):void
{
//some codes
}
but when the statement Application.application.Destination.child.dispatchEvent(new AlgoEvent(AlgoEvent.GETFROMPARENT_LOCAL_EVENT)); is executed the debugger give the following run time exception:
TypeError: Error #1034: Type Coercion failed: cannot convert resources.events::AlgoEvent#4182239 to resources.events.AlgoEvent.
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at mx.core::UIComponent/dispatchEvent()[C:\autobuild\3.2.0\frameworks\projects\framework\src\mx\core\UIComponent.as:9298]
at components::Destination/sendTimeToChild()[E:\FlexProjects\MyApp\src\components\Destination.mxml:99]
at components::Destination/updateParameters()[E:\FlexProjects\MyApp\src\components\Destination.mxml:206]
at components::Destination/__CreateBasketButton_click()[E:\FlexProjects\MyApp\src\components\Destination.mxml:558]
I am not able to identify what is going wrong here.
Please help to solve this problem
This is my Event class
public class AlgoEvent extends Event
{
public static const GETFROMPARENT_LOCAL_EVENT:String = "getfromparent_local";
private var eventType:String;
public function AlgoEvent(eventType:String, bubbles:Boolean=false, cancelable:Boolean=false)
{
super(eventType,bubbles,cancelable);
this.eventType=eventType;
}
}
While debugging am getting error in this funcion of UIComponent class
override public function dispatchEvent(event:Event):Boolean
{
if (dispatchEventHook != null)
dispatchEventHook(event, this);
return super.dispatchEvent(event);
}
Excaxtly this line gives the error: dispatchEventHook(event, this);
Import the AlgoEvent class in the main application and create a reference to it.
import resources.events.AlgoEvent;
private var dummyEvent: AlgoEvent;
Some explanations for this could be found here: Module domains
If your custom event doesn't carry any special event properties you could workaround your problem by using the standard Event class.
dispatchEvent(new Event(AlgoEvent.GETFROMPARENT_LOCAL_EVENT));
I had the same problem when dispatching, solved overriding two functions:
override public function clone():Event
{
return new AlgoEvent(type, bubbles, cancelable);
}
override public function toString():String
{
return formatToString("AlgoEvent","type"","bubbles","cancelable","eventPhase");
}
hope it helps out :)
Mr. splash suggested a solution which worked fro me:
Try to make the Custum Event (Algo Event in my case) class known to the main application.
I.e import it in the main application and create a variable of it..
And it works for a main reason>>when we try to communicate betwwen the modules using event dispatching what happens is :the modules are loaded at the run time but the classes like event classes are linked to the modules at the run time..
But the Event class is compiled before the modules are loaded..
application defines a Custum Event Class at compile time, and the module defines its own Custum Event Class when it is published. Then when the application is run, the Custum Event Class dispatched in the application doesn't match the one in the module
swf.
For the problem which is causing this error one can check the link:
http://www.kirupa.com/forum/showthread.php?t=320390
and also
http://www.jeffdepascale.com/index.php/flash/custom-events-in-loaded-swf-files/
Mate framework takes care of all this.
It gives you a global event bus, for all modules in your app.
http://mate.asfusion.com/
Try to override the clone() method in your customized Event,AlgoEvent.
Add the following code to your AlgoEvent.as class and try:
override public function clone():Event{
return new AlgoEvent(eventType,bubbles,cancelable);
}
HTH.
Your custom Event class should look like this:
public class AlgoEvent extends Event
{
public static const GETFROMPARENT_LOCAL_EVENT:String = "getfromparent_local";
public function AlgoEvent(type:String, bubbles:Boolean=false, cancelable:Boolean=false)
{
super(type, bubbles, cancelable);
};
override public function clone():AlgoEvent
{
return new AlgoEvent(type, bubbles, cancelable);
};
};
You should use the Event's inherited type property instead of creating a new one.
Also, the UIComponent has it's own dispatchEvent method, so you don't have to create your own - only if it works differently to the inherited one.
Regards,
Rob
Okay, it must be said that what you're doing, from an architectural standpoint, is wrong. Calling Application.application is bad for so many reason, especially if you're then starting to go down the display tree. The second any of the children changes, your build is now broke, and you won't know that until runtime because it's a module.
What you need is an application framework. A way to increase complexity without decreasing maintainability. There are many out there, but my personal favorite is Parsley. I've used it on many very large projects with much success. The problem you're trying to solve right now, dispatching one event where the other module listens for it, is extremely trivial (can be done in about 3 lines of code).
I recommend you look it over as well as my presentation on an introduction to parsley.
I refer to this site link text
Using the wrong event name in the
[Bindable] tag can cause your
application to not bind your property,
and you will not even know why. When
you use the [Bindable] tag with a
custom name, the example below looks
like a good idea:
public static const EVENT_CHANGED_CONST:String = "eventChangedConst";
private var _number:Number = 0;
[Bindable(event=EVENT_CHANGED_CONST)]
public function get number():Number
{
return _number;
}
public function set number(value:Number) : void
{
_number = value;
dispatchEvent(new Event(EVENT_CHANGED_CONST));
}
The code above assigns a static
property to the event name, and then
uses the same assignment to dispatch
the event. However, when the value
changes, the binding does not appear
to work. The reason is that the event
name will be EVENT_CHANGED_CONST and
not the value of the variable.
The code should have been written as
follows:
public static const EVENT_CHANGED_CONST:String = "eventChangedConst";
private var _number:Number = 0;
[Bindable(event="eventChangedConst")]
public function get number():Number
{
return _number;
}
public function set number(value:Number) : void
{
_number = value;
dispatchEvent(new Event(EVENT_CHANGED_CONST));
}
I agree, the wrong example does look like a good idea and I would do it that way because I think it's the right way and avoids the possibility of a typing error. Why is the name of the constant used instead of it's value? Surely this can't be right?
I appreciate your insights
Because the standard Flex compiler isn't that clever at times... and I feel your pain! I've complained about this exact problem more than a few times.
If I remember correctly, it's because the compiler does multiple passes. One of the early passes changes the Metadata into AS code. At this point in the compiler it hasn't parsed the rest of the AS code, so its not capable of parsing Constants or references to static variables in other files.
The only thing I can suggest is sign up to the Adobe JIRA, vote for the bug, and hope that the compiler fixes in 4.5 bring some relief.
I've written a class as follows. I've written it taking into consideration that its mainly for use on the web (i.e. it will be used from aspx pages).
public class TestHelper
{
public TestHelper()
{
HttpContext ctxt = HttpContext.Current;
IHttpHandler RequestHandler = ctxt.Handler;
Page CurrentPage;
CurrentPage = (Page)RequestHandler;
CurrentPage.Unload += new EventHandler(CurrentPage_Unload);
Debug.Print("Open all connection here...");
}
void CurrentPage_Unload(object sender, EventArgs e)
{
Debug.Print("Close all connection here...");
}
}
And I've written my aspx page's code behind like this:
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
TestHelper helper = new TestHelper();
helper = null;
}
}
In spite of assigning helper to 'null' I find that CurrentPage_Unload() gets executed. Why is this behaviour so? What is this behaviour generally called?
The reason why I've written the class in that style was because I thought I could best manage my db connections in a central fashion in the class. Usually people would call methods on the object like helper.IsValid() followed by helper.ProfileExists() in the aspx code behind. Each of those methods would have their own db connection objects(IDbConnection), and their corresponding Open() & Close() calls to open/close db connection. I just felt that we should only do this only once in code. Hence I used the constructor to open db connections, and the Page object's unload event to close the connection objects. Are there any pitfalls to writing classes this way?
What is happening is you're attaching a delegate to the Unload event of the page. Even after your variable has been set to null, your page still exists and still has an Unload event which still holds a reference to the delegate you added to it.
To remove a delegate you need to use -= syntax.
CurrentPage.Unload -= new EventHandler(CurrentPage_Unload);
Assigning null to a variable does not end its actual lifetime. Because .NET uses a non-deterministic garbage collection system (where objects are periodically purged based on several criteria, rather than as soon as they fall out of scope), you cannot rely on an object ever being collected before the process that created it ends.
Furthermore, because you're attaching an event handler (meaning a delegate, which includes a reference to your newly-constructed instance) to another object, you're extending the viable lifetime of your object as well. As long as that event handler is attached, your object cannot be collected until the object it's attached to is eligible.
You have to think about what happens when you execute the line
helper = null;
You simply have a reference to an object. When you assign that object to null, you're simply setting your reference to null. Nothing has happened to the object. Consider the following code:
var first = new object();
second = first;
first = null;
Would second now be null? You can think of a reference as simply a number - it's simply the address of the object in memory.
The .NET garbage collector simply looks at objects and checks if there are any references to that object. If not, it will remove that object.