I'm newish to flex an have recently hit a snag casting.
this is the code I'm running.
/**
* return background definition depending on time
*/
private function findBackgroundItem( relativeTime : Number ) : CSBackgroundItem
{
if( this.backgroundItems == null ) return null;
var result :CSBackgroundItem = null;
var relative:Date = new Date(relativeTime);
for( var i : Number = 0; i < this.backgroundItems.length; i++ )
{
// backgroundItems is an Ilist of CSBackgroundItem.
var colourItem : CSBackgroundItem = CSBackgroundItem( this.backgroundItems.getItemAt( i ) );
// other stuff here
}
return result;
}
The problem occurs when the IList.getItemsAt() result is cast to the CSBackgroundItem variable colourItem. The following error is thrown
TypeError: Error #1034: Type Coercion failed: cannot convert com.mystuff::CSBackgroundItem#650e8dd1 to com.mystuff.CSBackgroundItem.
If I use the 'as' keyword I get cast results in the colourItem being null. Using the debugger shows that the list is not empty and is indeed populated with CSBackgroundItem objects.
Now this is the wacky bit.. this code works, the first time the module it's in loads.. subsequent loads (after unloading it) throw the exception.
Can anyone shed any light on why this might happen?
FYI, a type loaded into a child ApplicationDomain can be cast to a type (that it extends/implements) in the parent ApplicationDomain.
Eg.
loader.applicationDomain = ApplicationDomain.currentDomain; // parent domain
loader.applicationDomain = new ApplicationDomain(ApplicationDomain.currentDomain); // child domain
loader.applicationDomain = new ApplicationDomain(); // new domain
I think I may have found the answer..
My guess is the module is loading in a different ApplicationDomain.. which would mean you can't cast from the same type in the current domain..
As I understand this is vaguely similart to different Java ClassLoaders loading the same class.
I'll post again once I've confirmed it
Yup.. that works..
here is the fix i used in MXML style..
<mx:ModuleLoader id="loader" x="10" y="10" width="100%" height="100%" applicationDomain="{ApplicationDomain.currentDomain}"/>
the equivilant actionscript would be
loader.applicationDomain = ApplicationDomain.currentDomain;
Related
I have refactored a bit my code, so i need a pointer that could contain multiple liste types :
owl_list = new Gee.LinkedList<OpenWithAction> ();
a_list = new Gee.LinkedList<OpenAppAction> ();
Gee.List* any_list = null;
So i have a pointer any_list which i can use to access either owl_list or a_list (depending on a switch no present here, but assume there is)
if (!any_list.size)
return null;
But this will fail as valac throws at me error: The name `size' does not exist in the context of `Gee.List*'
if (!any_list.size)
I haven't done any C,C++ since a very long time and I'm no vala expert, since i use more typeless languages, but is there any way this could work ?
EDIT:
I just tried
fieldType = OpenWithAction.get_type();
if (!(any_list as Gee.List<fieldType>).size)
error: The type name `fieldType' could not be found
if (!(any_list as Gee.List<fieldType>).size)
Obviously I'm doing something wrong, what i'm trying to do is : Vala: determine generic type inside List at runtime, i just can"t manage to implement it.
return null;
EDIT 2:
I just solved partially my problem :
As said by #jens-mühlenhoff, yes OpenWithAction and OpenAppAction have a common ancestor and it is GLib.Action
So all i had to do is declare :
Gee.List<Action> any_list = null;
instead of
Gee.List* any_list = null;
now foreach (var action in any_list) is working, but i'm still getting an error with
if (any_list->size == null)
return null;
error: The name `size' does not exist in the context of `Gee.List<Synapse.Action>?'
if (any_list->size == null)
another try is :
if (!any_list.size)
return null;
Operator not supported for `int'
if (!any_list.size)
any_list is a pointer, so you can't use the . operator. Try any_list->size.
Two things i was doing wrong :
1-
Like in C# i should not have used a pointer if not needed. So using :
Gee.List<Action> any_list = null; is just working fine. The explanation is that OpenWithAction and OpenAppAction have a common ancestor class, So declaring a List with that type is just working fine ( on the other hand i don't know in the case they didn't have a common ancestor).
2- int type can't be used as bool type so if (any_list.size == 0) would work whereas if (!any_list.size) would throw an error
Thanks every one for helping :)
I receive the following error when I try to run my code. I haven't managed to solve it yet, please Help:
edit: Marked with * where it fails.
>
public IQueryable<Video> GetVideos([QueryString("id")] int? categorieId)
{
var _db = new TeleviziuneAcademicaAspSilverlight.Models.VideoContext();
IQueryable<Video> query = *_db.Videos;*
if (categorieId.HasValue && categorieId > 0)
{
query = query.Where(v => v.CategorieID == categorieId);
}
return query;
Change
IQueryable<Video> query =
to
IQueryable<Appname.Models.Video> query =
The reason for your error is that you have the type Video defined twice and because of using a short type name you accidentally reference not the one Video you should.
Also change it in the method's return value
public IQueryable<Appname.Models.Video> GetVideos( ... )
You seem to have two classes called Video. If you need both, you'll need to project from one to the other before your return statement:
return query.Select(dbVideo => new Appname.Video()
{
Prop1 = dbVideo.Prop1,
Prop2 = dbVideo.Prop2,
// etc.
});
Though you'll probably need to change the return type to an IEnumerable<> if you do that.
If you can just work with Appname.Models.Video, change IQueryable<Video> to IQueryable<Appname.Models.Video> in the method signature and the method body.
I am trying to build a dynamic Property Accessor. Want something which is like really fast as close to calling the actually Property. Dont want to go the Reflection route as its very slow. So i opted to using DynamicAssembly and inject IL using ILGenerator. Below is the ILGenerator related code which seems to work
Label nulllabel = getIL.DefineLabel();
Label returnlabel = getIL.DefineLabel();
//_type = targetGetMethod.ReturnType;
if (methods.Count > 0)
{
getIL.DeclareLocal(typeof(object));
getIL.DeclareLocal(typeof(bool));
getIL.Emit(OpCodes.Ldarg_1); //Load the first argument
//(target object)
//Cast to the source type
getIL.Emit(OpCodes.Castclass, this.mTargetType);
//Get the property value
foreach (var methodInfo in methods)
{
getIL.EmitCall(OpCodes.Call, methodInfo, null);
if (methodInfo.ReturnType.IsValueType)
{
getIL.Emit(OpCodes.Box, methodInfo.ReturnType);
//Box if necessary
}
}
getIL.Emit(OpCodes.Stloc_0); //Store it
getIL.Emit(OpCodes.Br_S,returnlabel);
getIL.MarkLabel(nulllabel);
getIL.Emit(OpCodes.Ldnull);
getIL.Emit(OpCodes.Stloc_0);
getIL.MarkLabel(returnlabel);
getIL.Emit(OpCodes.Ldloc_0);
}
else
{
getIL.ThrowException(typeof(MissingMethodException));
}
getIL.Emit(OpCodes.Ret);
So above get the first argument which is the object that contains the property. the methods collection contains the nested property if any. for each property i use EmitCall which puts the the value on the stack and then i try to box it. This works like a charm.
The only issue is if you have a property like Order.Instrument.Symbol.Name and assume that Instrument object is null. Then the code will throw an null object exception.
So this what i did, i introduced a null check
foreach (var methodInfo in methods)
{
getIL.EmitCall(OpCodes.Call, methodInfo, null);
getIL.Emit(OpCodes.Stloc_0);
getIL.Emit(OpCodes.Ldloc_0);
getIL.Emit(OpCodes.Ldnull);
getIL.Emit(OpCodes.Ceq);
getIL.Emit(OpCodes.Stloc_1);
getIL.Emit(OpCodes.Ldloc_1);
getIL.Emit(OpCodes.Brtrue_S, nulllabel);
getIL.Emit(OpCodes.Ldloc_0);
if (methodInfo.ReturnType.IsValueType)
{
getIL.Emit(OpCodes.Box, methodInfo.ReturnType);
//Box if necessary
}
}
Now this code breaks saying That the object/memory is corrupted etc. So what exactly is wrong with this code. Am i missing something here.
Thanks in Advance.
Previously, if you had consecutive properties P returning string and then Q returning int, you would get something like this:
...
call P // returns string
call Q // requires a string on the stack, returns an int
box
...
Now you have something like this:
...
call P // returns string
store // stores to object
... // load, compare to null, etc.
load // loads an *object*
call Q // requires a *string* on the stack
store // stores to object *without boxing*
...
So I see two clear problems:
You are calling methods in such a way that the target is only known to be an object, not a specific type which has that method.
You are not boxing value types before storing them to a local of type object.
These can be solved by reworking your logic slightly. There are also a few other minor details you could clean up:
Rather than ceq followed by brtrue, just use beq.
There's no point in doing Stloc_1 followed by Ldloc_1 rather than just using the value on the stack since that local isn't used anywhere else.
Incorporating these changes, here's what I'd do:
Type finalType = null;
foreach (var methodInfo in methods)
{
finalType = methodInfo.ReturnType;
getIL.EmitCall(OpCodes.Call, methodInfo, null);
if (!finalType.IsValueType)
{
getIL.Emit(OpCodes.Dup);
getIL.Emit(OpCodes.Ldnull);
getIL.Emit(OpCodes.Beq_S, nulllabel);
}
}
if (finalType.IsValueType)
{
getIL.Emit(OpCodes.Box, methodInfo.ReturnType);
//Box if necessary
}
getIL.Emit(OpCodes.Br_S, returnLabel);
getIL.MarkLabel(nulllabel);
getIL.Emit(OpCodes.Pop);
getIL.Emit(OpCodes.Ldnull);
getIL.MarkLabel(returnlabel);
Note that we can get rid of both locals since we now just duplicate the top value on the stack before comparing against null.
I'm currently trying to implement an automated bug reporter for a Flex application, and would like to return error messages to a server along with the function/line number that caused the error. Essentially, I'm trying to get the getStackTrace() information without going into debug mode, because most users of the app aren't likely to have the debug version of flash player.
My current method is using the UncaughtErrorEvent handler to catch errors that occur within the app, but the error message only returns the type of error that has occurred, and not the location (which means it's useless). I have tried implementing getStackTrace() myself using a function name-grabber such as
private function getFunctionName (callee:Function, parent:Object):String {
for each ( var m:XML in describeType(parent)..method) {
if ( this[m.#name] == callee) return m.#name;
}
return "private function!";
}
but that will only work because of arguments.callee, and so won't go through multiple levels of function calls (it would never get above my error event listener).
So! Anyone have any ideas on how to get informative error messages through the global
error event handler?
EDIT: There seems to be some misunderstanding. I'm explicitly avoiding getStackTrace() because it returns 'null' when not in debug mode. Any solution that uses this function is what I'm specifically trying to avoid.
Just noticed the part about "I don't want to use debug." Well, that's not an option, as the non-debug version of Flash does not have any concept of a stack trace at all. Sucks, don't it?
Not relevant but still cool.
The rest is just for with the debug player.
This is part of my personal debug class (strangely enough, it is added to every single project I work on). It returns a String which represents the index in the stack passed -- class and method name. Once you have those, line number is trivial.
/**
* Returns the function name of whatever called this function (and whatever called that)...
*/
public static function getCaller( index:int = 0 ):String
{
try
{
throw new Error('pass');
}
catch (e:Error)
{
var arr:Array = String(e.getStackTrace()).split("\t");
var value:String = arr[3 + index];
// This pattern matches a standard function.
var re:RegExp = /^at (.*?)\/(.*?)\(\)/ ;
var owner:Array = re.exec(value);
try
{
var cref:Array = owner[1].split('::');
return cref[ 1 ] + "." + owner[2];
}
catch( e:Error )
{
try
{
re = /^at (.*?)\(\)/; // constructor.
owner = re.exec(value);
var tmp:Array = owner[1].split('::');
var cName:String = tmp.join('.');
return cName;
}
catch( error:Error )
{
}
}
}
return "No caller could be found.";
}
As a side note: this is not set up properly to handle an event model -- sometimes events present themselves as either not having callers or as some very weird alternate syntax.
You don't have to throw an error to get the stack trace.
var myError:Error = new Error();
var theStack:String = myError.getStackTrace();
good reference on the Error class
[EDIT]
Nope after reading my own reference getStackTrace() is only available in debug versions of the flash player.
So it looks like you are stuck with what you are doing now.
I have a DropdownList that shows a list of providers & the Provider associated with that Patient must be selected.
The Dropdown list:
<s:DropDownList id="providerList"
width="80%"
fontSize="12"
fontWeight="bold"
selectionColor="white"
creationComplete="providerList_creationCompleteHandler(event)"
dataProvider="{model.practiceProviderList.practiceProviders}"/>
where practiceProviders is an ArrayCollection
The CreationCompleteHandler function:
protected function providerList_creationCompleteHandler(event:FlexEvent):void
{
var firstN:String;
var lastN:String;
var providerObj:Provider = new Provider();
if (model.patientDetails.patientDetail.patientProviders != null && model.patientDetails.patientDetail.patientProviders.length > 0)
{
firstN = patientDetailsModel.patientDetails.patientDetail.patientProviders.getItemAt(0).provider.providerName.firstName;
lastN = patientDetailsModel.patientDetails.patientDetail.patientProviders.getItemAt(0).provider.providerName.lastName;
for (var count:int = 0; count < patientDetailsModel.practiceProviderList.practiceProviders.length; ++count)
{
providerObj = patientDetailsModel.practiceProviderList.practiceProviders.getItemAt(count, 0).provider as Provider;
if (providerObj.providerName.firstName == firstN && providerObj.providerName.lastName == lastN)
{
this.providerList.selectedIndex = count;
}
}
}
}
The issue is when I go to this page the first time, the error is :
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at com.newwavetechnologies.modules::demographics/providerList_creationCompleteHandler()[C:\harish\flex\apps\workspace\dataCollection-flexUserInterface\src\com\newwavetechnologies\modules\demographics.mxml:166]
at com.newwavetechnologies.modules::demographics/__providerList_creationComplete()[C:\harish\flex\apps\workspace\dataCollection-flexUserInterface\src\com\newwavetechnologies\modules\demographics.mxml:359]
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at mx.core::UIComponent/dispatchEvent()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\core\UIComponent.as:12266]
at mx.core::UIComponent/set initialized()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\core\UIComponent.as:1577]
at mx.managers::LayoutManager/doPhasedInstantiation()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\managers\LayoutManager.as:759]
at mx.managers::LayoutManager/doPhasedInstantiationCallback()[E:\dev\4.0.0\frameworks\projects\framework\src\mx\managers\LayoutManager.as:1072]
where line 166 is:
if (providerObj.providerName.firstName == firstN && providerObj.providerName.lastName == lastN)
The providerObj is null the first time. But when hit back and come to the same page again, everything works fine and 1 of the providers in the list is selected correctly.
Probably I think the first time, the creationComplete handler method is called before the List is populated. The 2nd time when the call is made, the list is populated and the handler works fine. It would be great if someone can help me in this regard on how to go about this.
Thanks
Harish
It's hard to tell what's going on here, but the problem lies here:
providerObj = patientDetailsModel.practiceProviderList.practiceProviders.getItemAt(count, 0).provider as Provider;
There's a tonne of places in that line that Null pointer exceptions could occur.
Most likely - the practiceProvider returned at position count doesn't have a provider set. We can't see how this value is populated, but given this code works later, I'd say you've got a race condition happening - the data is being accessed before it's been set.
At very least, you should add a guardClause for this:
var practiceProviders:ArrayCollection = patientDetailsModel.practiceProviderList.practiceProviders;
for (var count:int = 0; count < practiceProviders.length; ++count)
{
providerObj = practiceProviders.getItemAt(count, 0).provider as Provider;
if (!providerObj)
continue;
// etc
}
The race condition is a little trickier, given the asyncronous natoure of flex server calls. (I'm assuming that you're loading the data from a remote server).
There's two approaches to solve this - either
defer execution of this method until the data has loaded - you could do this by adding an eventListener to the ResultEvent of the RemoteService
or
Don't worry about it the first time around, but re-execute the method whenever the data changes.
eg:
protected function providerList_creationCompleteHandler(event:FlexEvent):void
{
dataProvider.addEventListener(CollectionEvent.COLLECTION_CHANGE,onCollectionChange,false,0,true);
updateProviders();
// Rest of existing creationComplete code moved to updateProviders();
}
private function updateProviders()
{
// Code from existing creationComplete handler goes here
}
private function onCollectionChange(event:CollectionEvent):void
{
updateProviders();
}