Hey everyone so this is something that I have always had trouble trying to accomplish or understand. So I have my main Engine class calledescapeEngine where I have a private var nScore I want to be able to access this variables through a separate class called mcPlanets but I don't know how I would accomplish this. I know how to do the opposite but not how to access a var from my main Engine class. Can anyone help me out?
I am not sure what you are trying to do, but here is an example that may help you:
Inside esacapeEngine class (main), create a public var nString and new instance of mcPlanets.
// two lines in escapeEngine.as
var nScore = 0;
var mcPlant = new mcPlanets(this);
So, when you create new mcPlanets, pass in the reference (keyword 'this' in the parentheses). Now mcPlanets knows about your main class.
And now in mcPlanets class, write this:
public class mcPlanets
{
private var escapeEngine;
public function mcPlanets(main) // 'this' = 'main'
{
escapeEngine = main;
// access nScore defined in main class
escapeEngine.nScore = 5;
}
}
In this example, nScore must be a public variable, it could be a private but you should use 'get and set' methods.
Related
I'm new at Zenject(Extenject).
My dev environment: Win10, Unity2020, Extenject 9.2.0
Here is my question:
In installer bind the class
Container.Bind<AccountInfo>().AsCached();
Inject it at classA
private AccountInfo accountInfo;
[Inject]
private void Init(GameSetup _gameSetup, AccountInfo _accountInfo)
{
this.gameSetup = _gameSetup;
this.accountInfo = _accountInfo;
}
accountInfo.address = "xxx'; // works fine
Then inject AccountInfo to classB
private AccountInfo accountInfo;
[Inject]
private void Init(AccountInfo _accountInfo)
{
this.accountInfo = _accountInfo;
}
accountInfo.address = "xxx'; //NullReferenceException: Object reference not set to an instance of an object
Why accountInfo changed to null? AsCached() dosen't work? Or something worng else?
Help please~~ Thank you!
Here is my code:
Installer
"ClassA" inject GameSetup, and create instance, works fine
"ClassB" inject GameSetup, Error: null object
"ClassB" Creator, I'm trying use container.Instantiate() to create it
---update---
gameSetup still Null Object
There are two cases, when injection will not work properly in your code.
The code, that uses injected object is executed before Init. For example if this code is placed in the construcor.
You create your GameObject/Component in runtime whithout using IInstantiator. While you use Znject you always should use IInstantiator to create objects. To do it you should inject IInstantiator to the object, that creates another objects. IItstantiator is always binded in the container by default, so you don't have to bind it manually. For example:
public class Creator : MonoBehaviour {
[SerializeField]
private GameObject _somePrefab;
private IInstantiator _instantiator;
[Inject]
public void Initialize(IInstantiator instantiator) {
_instantiator = instantiator;
}
private void Start() {
// example of creating components
var gameObj = new GameObject(); // new empty gameobjects can be created without IInstantiator
_instantiator.InstantiateComponent<YourComponentClass>(gameObj);
// example of instantiating prefab
var prefabInstance = _instantiator.InstantiatePrefab(_somePrefab);
}
}
Not an expert but I think that passing IInstantiator or the container around is not a good practice. If you need to create injected instances at runtime, then you need a Factory.
From the documentation
1.- Best practice with DI is to only reference the container in the composition root "layer"
Note that factories are part of this layer and the container can be referenced there (which is necessary to create objects at runtime).
2.- "When instantiating objects directly, you can either use DiContainer or you can use IInstantiator, which DiContainer inherits from. However, note that injecting the DiContainer is usually a sign of bad practice, since there is almost always a better way to design your code such that you don't need to reference DiContainer directly".
3.- "Once again, best practice with dependency injection is to only reference the DiContainer in the "composition root layer""
Where and how to set variable value that is available in all controllers. I don't wont to use zend registry and don't want to extend Zend_Controller_Action. Is there is another way? I just want for example to set:
$a = "test";
and in Index controller to dump it:
class IndexController extends Zend_Controller_Action {
public function indexAction(){
var_dump($a);
}
}
Global vars ruin the purpose of object oriented programming... use namespace or custom configs.
Solution 1
Use session Zend_Session_Namespace, here is documentation on how to Zend_Session_Namespace.
Set set the value in namespace in bootstrap or something (wherever you see fit)
Retrieve the value from namespace in you controller/model/other
Solution 2
Alternatively, you can create some new class with static properties and use it's setters/getters to set and retrieve values.
E.g.
class SomeClass
{
static $hello = 'world';
}
class IndexController extends Zend_Controller_Action
{
public function indexAction()
{
var_dump(SomeClass::$hello);
}
}
You can add variables to the request object:
$this->getRequest()->setParam('a', 'hello');
Then retrieve it using:
$this->getRequest()->getParam('a);
But that is not the best way of doing it as you might accidentally overwrite a parameter a needed parameter.
I Compose the Container at startup and later on create a Instance of a object that has a Import property. This property is Null when I try to use it.
How does MEF handle objects created later on. I refuse to believe you have to instantiate all objects at startup.
You don't have to create instances as soon as you create the container, that wouldn't be any real help for anyone. How are you creating your instances? Here are some examples, given an example class:
[Export]
public class MyClass
{
[Import]
public MyOtherClass OtherClass { get; set; }
}
I could:
var myClass = container.GetExportedValue<MyClass>(); // This would automatically compose.
var myExport = container.GetExport<MyClass>();
var myClass = myExport.Value; // This would automatically compose.
var myClass = new MyClass();
container.SatisfyImportsOnce(myClass); // Manually compose your part.
Or manually wind it all together using a CompositionBatch, etc.
Is there any way I can compose (or get an exported value) with a specific instance as one of it's dependencies?
I have something like this:
public interface IEntityContext
{
IEntitySet<T> GetEntitySet<T>();
}
[Export(typeof(IEntitySet<MyEntity>))]
class MyEntitySet
{
public MyEntitySet(IEntityContext context)
{
}
}
// then through code
var container = ...;
using (var context = container.GetExportedValue<IEntityContext>())
{
var myEntitySet = context.GetEntitySet<MyEntity>();
// I wan't myEntitySet to have the above context constructor injected
}
I'm trying to mock something like entity framework for testability sake. Not sure though if I would want to go down this road. Anyway, should I be creating a new container for this very purpose. A container specific to the mocking of this one IEntityContext object.
So, if my understanding is correct, you want to be able to inject whatever IEntityContext is available to your instance of MyEntitySet?
[Export(typeof(IEntitySet<MyEntity>))]
public class MyEntitySet : IEntitySet<MyEntity>
{
[ImportingConstructor]
public MyEntitySet(IEntityContext context)
{
}
}
Given that you then want to mock the IEntityContext? If so, you could then do this:
var contextMock = new Mock<IEntityContext>();
var setMock = new Mock<IEntitySet<MyEntity>>();
contextMock
.Setup(m => m.GetEntitySet<MyEntity>())
.Returns(setMock.Object);
Container.ComposeExportedValue<IEntityContext>(contextMock.Object);
var context = Container.GetExportedValue<IEntityContext>();
var entitySet = context.GetEntitySet<MyEntity>();
(That's using Moq)
You can use your existing CompositionContainer infrastructure by adding an exported value.
Does that help at all? Sorry it doesn't seem exactly clear what you are trying to do...
I am looking for some help and I hope that some good soul out there will be able to give me a hint :)
I am building a new application by using MVVM Light. In this application, when a View is created, it instantiates the corresponding ViewModel by using the MEF import.
Here is some code:
public partial class ContractEditorView : Window
{
public ContractEditorView ()
{
InitializeComponent();
CompositionInitializer.SatisfyImports(this);
}
[Import(ViewModelTypes.ContractEditorViewModel)]
public object ViewModel
{
set
{
DataContext = value;
}
}
}
And here is the export for the ViewModel:
[PartCreationPolicy(CreationPolicy.NonShared)]
[Export(ViewModelTypes.ContractEditorViewModel)]
public class ContractEditorViewModel: ViewModelBase
{
public ContractEditorViewModel()
{
_contract = new Models.Contract();
}
}
Now, this works if I want to open a new window in order to create a new contract... or in other words, it is perfect if I don't need to pass the ID of an existing contract.
However let's suppose I want to use the same View in order to edit an existing contract. In this case I would add a new constructor to the same View, which accepts either a model ID or a model object.
"Unfortunately" the ViewModel is created always in the same way:
[Import(ViewModelTypes.ContractEditorViewModel)]
public object ViewModel
{
set
{
DataContext = value;
}
}
As far as I know, this invokes the standard/no-parameters constructor of the corresponding ViewModel at composition-time.
So what I would like to know is how to differentiate this behavior? How can I call a specific constructor during composition time? Or how can I pass some parameters during the Import?
I really apologize if this question sounds silly, but I have only recently started to use MEF!
Thanks in advance,
Cheers,
Gianluca.
You CAN do this. Check out the Messenger implementation in MVVM-Light. You can pass a NotificationMessage(Of Integer) to send the right ID to the view model. The view model has to register for that type of message, and load it when a message is sent.
MEF Imports by default only have a parameterless constructor.