I currently have a problem because I can't figure out how to solve the problem. I have an actor that is supposed to call a function in the other actor on the "Begin Overlap Event".
The other actors that can trigger this event are all based on a parent blueprint in which the function was also implemented. My first idea was to cast directly to the parent BP. But that failed.
Maybe you can understand better what I mean with this little graphic.
Do you have an idea how I can solve this?
you can't call function GetDamage() from the variable "Target" because it is AActor class - he doesn't know anything about a child's functionality.
if your overlapped actor ("OtherActor") is TowerBaseBP with the GetDamage then you absolutely can cast to it. You can do it until set "Target" (in this case need to change this variable from AActor to the TowerBaseBP), or cast until calling relevant function GetDamage().
check "OtherActor" on the ComponentBeginOverlap - Is it your child actor with the needed parent?
if so cast to the Parent class (not the child one) and set your "Target" variable (need to be Parent type);
then try to call GetDamage() from Target;
if you can't still call it, I have two suggestions:
a) check your child classes - maybe you overrided GetDamage() and
forgot to add CallToParent function;
b) carefully check "OtherActor", and "Target" from points 1-3;
Related
I've edited the question to make what I want to obtain clearer.
Here's the original question:
I'm working on a class that inherits from Control which will be used in my View and includes some Dependency Properties.
One of these DPs is an IEnumerable(Of RfidTag) and will be bound to an ObservableCollection(Of RfidTag) inside the VM.
The class RfidTag is defined as public class in the same file where the VM's class resides.
The questions are:
1. is it a good practice to expose a VM-related class to a Control class?
2. is the VM source file a good place for the RfidTag class?
UPDATE 1
In my application logic (I think I could say in my Model) there is an event published throught an Eventaggregator. The event's payload is a List of ModelRfidTag (that is the model class).
My VM subscribes to this event and I made the RfidTag class to wrap my Model class and provides some additional properties related only to the VM.
When the event handler inside the VM is executed, it makes an ObservableCollection(Of RfidTag) bindable from the view.
Then in the View I've a bounch of my control instances like that
<c:RfidTagPresenter
TagPosition="1"
Collection="{Binding RfidTagList, Mode=OneWay}" />
Then in my RfidTagPresenter (the class that inherits from Control) I've a DP of type RfidTag (called RfidTagResult) that returns the object in the OC which has the Position property (property available inside the RfidTag class) equal to the value set by the TagPosition DP.
In this way, the ControlTemplate of the RfidTagPresenter can bind its elements to the desired object.
This is the simplification of what I want to make. In the actual application there are some other DPs on which the RfidTagResult selection is performed
UPDATE 2
After a bit of research, seem that I can solve one problem with an indexed property that return (in the get method) the object from the collection I want to bind.
However a problem still exist: My control need to have a DP of type of RfidTag so that the relative ControlTemplate can bind to the property declared in the RfidTag class.
So: Is it possible (read: a good practice) to have a DP of a type that is a VM related class?
In other words: Can a custom control know about the class type used by the VM?
I will try to go all over your question (if I miss something let me know) but first you should explain the purpose of binding a Collection in a control as a DP.
is it a good practice to expose a VM-related class to a Control class?
RfidTag, I suppose, is a Model. What you are really doing here is binding a Model in your control which go against the MVVM pattern. You should think about the next question... Do you really need all your RfidTag to be shown in the View ? If you need to show a name, an ID... you could just create an IEnumerable<string> as DP (which is correct) and then in your VM instead of an ObservableCollection<RfidTag> you would have an ObservableCollection<string>.
Some simple theory. In MVVM, VM adapts the Model to the View. So your VM should have everything that will be shown in your View.
is the VM source file a good place for the RfidTag class?
RfidTag is a Model so there's no better place for it :)
I Have a variable that updates every time i move my cube in the level blueprint , now i want to access this variable from multiple class blueprints , what do I do , I tried casting to gamestate but didn't succeed , I am really new to ue4 if you could explain in details please
edit: sorry for not adding details ,
The var I want to access is an integer named cube_side that tells me what side the cube is on every time I move , all of this happens in the level bp , I want to access this variable to see what side the cube is on from other class blueprints ->
here are some details in a picture
I know it's not good to code everything in the level blueprint , but it's too late now , I only need to transfer the var cube_side to other class blueprints so the other object can change depending what side the cube is on.
Create an Actor Class for your logic/functionality. Then use Get all actors of class (choose your class) -> Get a copy -> get variable
Communication with the level blueprint is rather tricky in UE4, since they are not as persistent as e.g. the GameMode, and therefore shouldn't be accessed directly (Imagine older games like Final Fantasy where a new level was loaded every time you stepped outside a boundary, so relying on it could potentially break your actors or crash the game due to nullptrs).
It's a little hacky, but works:
Move the variable inside the cube-blueprint. Add an event dispatcher to the cube, if it is moved, call it and pass the variable in.
Select the cube in the editor, open the level blueprint, right-click, "add reference to selected actor" (the cube must be part of a blueprintclass, not only a static mesh dragged in, though), and bind the event dispatcher inside the Level BP.
Create a function inside every blueprint that needs access to the variable, which does whatever it should do, depending on the variable.
The custom event of the Level Bp (that was bound to the Event Dispatcher of the cube), needs references to all actors that have to work, when the variable changes and call each Actors function (you can get the references like you got the one from the cube)
Then, every time the variable changes, the Level BP is notified, the custom Event is executed and this custom event calls all the actor's functions.
Event Dispatchers explained
This is a huge wastage of functions/code, since you only need it for this one level and may never use it again. Avoid this in the future, by not relying on the level BP so much.
You can use GameStateBP to create and store all variables that you need in game, in GameModeBP create functions to get and set this variables via Get Game State function and then function Cast To GameState and then logic. After that from any blueprint access it using Get Game Mode -> Cast to you GameMode -> use your function to set or get data from GameState.
In need to create an Akka2 actor (derived from UntypedActor) as a child of an existing actor (also derived from UntypedActor). The only reference I have to the parent actor is an ActorRef. Is there any way to do this? I'd like to call the parent's UntypedActorContext.actorOf() method, but don't know how to get a reference to it using the Akka API. Is there a better way of accomplishing my goal?
You cannot force someone to conceive against their will. Your actor needs to receive a message to which it responds by creating a new actor and send you the ref to that actor.
Can you change the code of the parent actor? You could for example add a handler for a message of type Props in your parent and create the child there. It is not possible to get the context outside of the actor class.
I've been reading up a bit about coffeescript's inheritance model and I have the feeling I'm on the fringes of an ideological debate which I really don't understand. So, I would be perfectly happy to find out that I'm just doing things in the wrong way.
Basically what I am doing is writing a set of widgets which, among other things, need to handle events on their DOM elements. I thought a good way to go about this would be to have a class method which would be called once, to delegate all the events which the widget might need. The base widget class might have some simple click handlers, while the subclass might add to that some mouseover handlers or extra click handlers.
However, it appears that I'm not supposed to try and do the equivalent of calling super() inside a static method. There is a workaround which exists, (this.__super__.constructor.METHODNAME() but I've seen a lot of suggestions that this isn't the best way to do what I'm trying to do. Has anyone got any insights on how I should structure this code? Keep using the workaround, or put all the delegation into a totally different place? I can't really just stick it in the prototype, since I won't necessarily have an instance to call the method on (or can I essentially still call a method on the prototype from a static context, like putting SwatchableWidget.prototype.delegateEvents() into an onload function or something?
Here's a bit of code to illustrate what I'm talking about:
class Widget
#testProp: "ThemeWidget"
#delegateEvents: ->
console.log "delegate some generic events"
class SwatchableWidget extends Widget
#testProp2 = "SwatchWidget"
#delegateEvents: ->
console.log "delegate some specific swatchable widget events"
this.__super__.constructor.delegateEvents()
Widget.delegateEvents()
SwatchableWidget.delegateEvents()
Thanks for any help.
I suggest replacing
this.__super__.constructor.delegateEvents()
with
Widget.delegateEvents()
trying to use super to call static methods is not required (and doesn't make much sense)
I don't understand why delegateEvents would be a class-level method, or why Widget.delegateEvents have to be called again from SwatchableWidget.delegateEvents. If it's just class initialization code, you should put it in the class body directly:
class Widget
console.log "delegate some generic events"
...
#testProp: "ThemeWidget"
class SwatchableWidget extends Widget
console.log "delegate some specific swatchable widget events"
...
#testProp2 = "SwatchWidget"
I take it you're waiting for a specific DOM state before running this initialization code? Maybe I could suggest another approach if you told me a little bit more about the preconditions for delegateEvents.
It sounds like you want a different type of inheritance model where each inherited function of a certain type ("parent calling") will walk the inheritance tree and call all its parents with the same name.
You could call any direct parent functions in each child manually as you've written. Then it will float up the inheritance chain anywhere you specify such a relationship.
I would bind the parents delegate call in the constructor to a current class function
delegateparents =>
#call any parent class methods
I couldn't find any reference on how to use a parent form element in a subclassed form. May be because it's obvious to everyone but me. It's got me stumped. This is what I tried.
At first, within my form constructor I called
parent::__construct($options = null);
then accessed the parent elements like this
$type = parent::setName($this->type);
The problem was that ALL the parent form elements would display whether explicitly called or not. Someone said, "don't use __construct(), use the init() function instead. So I changed the constructor to init(), commented out the parent constructor, then ran the form. It bombed saying it couldn't pass an empty value for setName(). I commented out all the seName() calls and the form ran, but only displayed the elements instantiated in the subclassed form.
My question is this: If I don't use the parent constructor, how do i get and use the parent's form elements?
Solved: Since the constructor was switched to init, the call to the parent also needed to be switched. Easy for someone with php background. Not so much for one who doesn't.
Use
parent::init();
Solved: Since the constructor was switched to init, the call to the parent also needed to be switched. Easy for someone with php background. Not so much for one who doesn't.
Use
parent::init();
You should learn OOP principles first. Obviously you have no understanding of it whatsoever. You need to call parent::init() in you Form_Class::init() method as you wrote, but why? Because otherwise the parent method is not called and is overriden by the From_Class method.
Other thing is that when you have a parent class "SuperForm" with input and submit, then your "SuperForm_Subclass" would have the same elements assigned. There is no need to use "parent::*" to access element (only exception would be if you used static SuperForm variable to store them - which makes no sense).
You can easily use $this->inputElement and $this->submitElement inside your SuperForm_Subclass like you would in the SuperForm class.
In your example you could used the __contruct() as good, but with the same condition of calling the parent constructor. You would be able to access elements generated there too...