I would like to be passing the variable from the thirdpersoncharacter to the blueprint animbp, if in case you have tbm alternatives accepted, I thank you
Generally you do not pass in values directly to the Animation Blueprint, the Animation Blueprint instead reads values from a reference to the Pawn Owner.
Related
I am writing a design-time level editor.
I would like my levels to be defined in JSON, and loaded/saved using Json serialization (Probably NewtonSoft)
The issue I have is this:
In order to have the objects be serializable, they cannot be Unity Objects (e.g. ScriptableObject) (and, indeed, I don’t need them to be – except
In order to bind custom editor stuff to the object’s properties, the objects need to be unity Objects.
I can’t figure out what to do – and figured people must be doing something similar, but my Google skills are failing me (and I have googled A LOT!
As a really simple example:
I have a class called Level, with a string field called LevelName
I have an EditorWindow which has a reference the current Level instance
If Level is a MonoBehaviour, I can say
_so = new SerializedObject(_level); and I can bind a field in my UI to the LevelName field
That works fine – but now I want to save the data – but when I try to serialise it I get an error:
NotSupportedException: rigidbody property has been deprecated
This, my searching tells me, is simply because you can’t serialize unity Object.
But if I change Level to be a POCO (i.e. not inheriting from anything) then the binding doesn’t work because _level is not a UnityEngine.Object
I feel I may be missing something really obvious, but for the moment I am stuck and would really appreciate any help or advice.
I need to control destruction of a value-class object in Matlab.
The problem is as following.
I have a some program (let's call it MyProg) that during execution creates a value-class object (lets call it MyValClass). MyValClass has a handle-class object as one of its properties (lets call it MyHandClass). That handle class initiates some events that MyProg listens to.
The problem appears is MyValClass object is destroyed (usually it happens on exceptions or user termination). I guess, that because there are still listeners listening to events of MyHandClass, the MyHandClass object is not destroyed, and remains in memory.
I would like to control the destruction of MyValClass object, so that I could implicitly delete its MyHandClass property. Is it possible?
Here is a bit of background on handle vs value classes:
Objects of a value class are not "destroyed", and they do not have a destructor method. Think of value classes as behaving like the variable a when you've set a = 1. a is not "destroyed" when you type clear a, there's just no variable a any more. Value objects are just data, like 1, and they don't get destroyed.
The above is true even if the value class has a method called delete. A delete method on a value class is just like any other method. It is not a destructor, and it does not get automatically called when the variable is cleared. It only gets called when you explicitly call it.
Handle classes always, whether you implement one or not, have a method called delete, which is a destructor method (i.e. is called when the object is destroyed). If you don't implement one, they will be given a default method called delete, which does nothing other than destroy the object. If you implement a delete method, MATLAB will run that when destroying the object. But there is always a delete method that is a destructor, even if you don't implement one.
So - to your question - if you wish to control the destruction of MyValClass, you must change it to become a handle class. If it's a value class, it is not destroyed and there's nothing to control.
There are other things you might be able to do instead of directly "controlling the destruction". For example, you create an onCleanup object. This is a class that does nothing but execute a user-specified function on its destruction (it's a handle class, so it can do this). So if your code exits because of an exception or user termination, the onCleanup destructor will execute. You could, for example, put some code in there that would explicitly find references to MyHandlClass and deleted them.
Hope that helps!
The destructor for value object may be necessary, for example, if the class is responsible for accessing data from file and you want to close file when your accessor goes out of scope. There are number of reasons why you would not want such class to be a handle class (e.g. weird behavior on array of objects)
Other reason is creating existing objects counter.
My solution is to define hidden property, delete_, and assign onCleanup(#()something) object to this property. The function, provided to onCleanup would close the files, decrement object counter etc....
Trying to add a class to an array. The class contain an object and an integer. However, when I destroy the SELF the class reference in the array is removed as well? How do I add by value?
UObjects are inherently a reference semantics entity. Their lifetime and memory management is controlled by the engine.
It sounds like HerbType should be a class reference, which you would spawn when necessary.
I need to create subclass of the Patch object's class in MATLAB 2014b but MATLAB does not allow me to do so:
Class 'matlab.graphics.primitive.Patch' is Sealed and may not be used as a superclass.
Is there a hack around this?
No - you can't subclass a class that is Sealed, and matlab.graphics.primitive.Patch is a built-in class, so you can't make a (hack) edit to unseal it.
The best you can do is to use an Adapter pattern - create your own class, storing a Patch as a private (and maybe hidden) property, and then wrap all its properties and ones of your own, implementing set and get methods that pass through the value to/from the underlying Patch. Do something similar for any methods of Patch that you need. You may also need to listen to property change events on the Patch and respond to them appropriately.
Then you can add your own methods as well, and/or modify the existing method and property behavior as required.
No. If the class is sealed, it shall not be derived from. There are probably good reasons why it has been chosen to be sealed; other classes may assume a particular implementation which you can override if you were to inherit from the class.
Exactly what the topic title says,
In which cases would you prefer using public functions to change local variables over just defining that variable as public and modifying it directly?
Don't expose the data members directly: using opaque accessors means you can change the implementation at a later date without changing the interface.
I should know. I take the short cut from time-to-time, and have had occasion to regret it.
Obviously if you want changing the variable to have some other effect on the object's state (like recalculating some other property of the object) you must use a mutator function.
If it's possible to set the variable to something that places the object in an invalid state, you should probably also use a mutator function. This way you can throw an exception (or return an error, or just ignore) if something illegal is about to happen. This does wonders for debugging.
But if some variables can be modified with mutator functions, and others are public, the programmer needs to keep track of which is which. This is a waste of time and effort so in some cases it's easiest to just use mutator functions for everything.
If you look at an object purely in term of service, you realize that exposing a variable is not a good way to expose those services.
The API must reflect what the object is all about (for it to achieve a high cohesiveness), and if you define a setValue(...), it is not so much because you need a way to -- today -- changes a variable, but because it makes sense for the object to expose this service.
So:
Don't provide accessors or mutator function to every single member of every single class you write. Only provide accessors/mutator functions if the accessors/mutator methods are a sensible and useful part of the class's interface (API).
Don't think of these methods as accessors or mutators. Instead, think of them as methods that access or mutate a certain abstract property of the object that happens to be represented by a single member today, but may be computed in a more complex manner tomorrow.
You should mention what language you are dealing with, since that will affect the answer.
Your first thought should be about the API to your class. If you want to keep that API stable (and you should!), then consider how you might change today's simple variable into a full-blown method later.
In many languages, you can't change a variable to a method without changing the calling code. C, C++, and Java fall into this category. Never use public variables in these languages, because you won't have any wiggle room later.
In Python, you can change a variable to a property without changing the callers, so you don't have to worry up front: use public variables.
C# I believe has properties that can let you change variables to methods transparently, but I am not sure.
If you want to change a variable inside a class, your best doing it through Properties.
Its not good practice to have variable's modified on the outside.
Think of future development too. You could put some logic behind a Property without changing the whole program.