Below is my parent class
public class Parent
{
//This method is intercept-able using **VirtualMethodInterceptor**
public virtual void Test()
{
//Do something
}
}
Below is my child class
public class Child:Parent
{
// This method directly not intercept-able but it calls base.Test() where Test is an intercept-able method
public void Demo(){
base.Test();
}
}
Now I want to resolve an instance of Child class using Unity where Demo method will be interceptable. Actually Demo method can't be interceptable as because it's not virtual but this method internally invoke base.Test() where Test is intercept-able. So how to resolve an interceptable instance of Child class?
It doesn't work If I register child class into an unity container like below
container.RegisterType<Child>(
new Interceptor<VirtualMethodInterceptor>(),
new InterceptionBehavior<Interceptor>()
)
Make sure you have done the following:
1) You added the Interception extension like this:
container.AddNewExtension<Interception>();
2) The WillExecute property of your interception behavior class returns true.
3) You obtain the Child instance from the container. This can be done directly like this:
Child chlid = container.Resolve<Child>();
Or by having Child as a dependency for some class, and then resolving the object graph that contains this class using the container.
Related
I'm studying blazor server.
Deployed a solution from a standard vs template.
Created two server-side services, TestService1 and TestService2.
In TestService1 i have task
GetMyData()
How can i call with task from TestService2?
If i trying
var serv1 = new TestService1()
i have to fill in all the variables of the constructor that is in TestService1.
What is easiest way?
In line with the comment on your question, the best way to go about this in Blazor is to utilize the built-in dependency injection mechanism.
I assume that your services look like the following:
public class TestService1
{
public object GetMyData()
{
}
}
public class TestService2
{
private readonly TestService1 _testService1 { get; set; }
public class TestService2(TestService1 ts1)
{
_testService1 = ts1;
}
public void DoesSomething()
{
var data = _testService1.GetMyData();
//...
}
}
First, you'd need to register these with Blazor at startup, so in your Startup.cs in the ConfigureServices method, add the following, assuming you have an empty constructor available for TestService1:
services.AddSingleton<TestService1>();
Because you'll need to instantiate an instance of TestService1 into TestService2 to call methods on it, you'll have to handle registration of TestService2 differently since you'll need to procure an instance of TestService1 from the DI service to instantiate it:
services.AddSingleton<TestService2>(s => {
var testService1 = s.GetService<TestService1>();
return new TestService2(testService1);
});
It's possible you may need to scope the services differently (e.g. used scoped instead of singletons). You can read about the differences here.
Now something is presumably calling TestService2 to kick all this off, so let's pretend it's running in a component in your Blazor app. You'd inject TestService2 into the component with the following:
#inject TestService2 _testService2
<h1>Hello!</h1>
#code {
protected override void OnInitialized()
{
_testService2.DoesSomething();
}
}
As part of the initialization then of this component, it'll automatically inject a TestService2 instance (based on the scoping you specified at DI initialization) to your component and will call the DoesSomething method on it. When injected, it looks to DI to instantiate the TestService1 service to the constructor as you've also specified, leaving it free to call that method and the call commences as intended.
Please let me know if you'd like any clarification somewhere!
The following example shows a scenario where I'm trying to implement a DI container. In this case, I'm trying to use Simple Injector or Microsoft.Extensions.DependencyInjection DI Container. I've seen code examples that start hitting around the target, such as here, but no bullseye as of yet.
Below is a general code sample that I would like to modify to use one of the aforementioned DI containers (Used Simple Injector for example). I could move the view out of the presenter constructor and set it as a property. However, I was hoping for a more eloquent solution also it is a dependency that needs to be injected.
I know .NET 4.7.2 has increased DI support functionality but the biggest benefit seems to be allowing dependencies to be easily injected into pages/user controls. For MVP architecture I need the concrete class of the page tied to its view interface so the DI container can resolve and pass into the presenter, as the presenter depends on the view. I've not seen an example of this implemented well other than Unity using its DependencyOverride, which can pass the concrete class at runtime.
public partial class UserLoginView : IUserLoginView
{
private UserLoginPresenter _userLoginPresenter;
protected override void OnLoad(EventArgs e)
{
//This is my problem:
//An error will be thrown "...contains the parameter with name
//'view' and type IUserLoginView, but IUserLoginView is not
//registered..."
_userLoginPresenter = SimpleInjectorDependencyInjector
.GetInstance<IDeveloperTestStatusPresenter>();
}
}
public class UserLoginPresenter : IUserLoginPresenter
{
private readonly IUserLoginView view;
private readonly IUserService _userService;
public UserLoginPresenter(IUserLoginView userLoginView,
IUserService userService)
{
this.view = userLoginView;
this._userService = userService;
}
public static class SimpleInjectorDependencyInjector
{
private static readonly Container container = new Container();
public static T GetInstance<T>() where T : class
{
return container.GetInstance<T>();
}
//Assume this is called from App on start
public static void RegisterClasses()
{
container
.Register<IUserLoginPresenter, UserLoginPresenter>();
container
.Register<IUserService, UserService>();
}
}
I was able to accomplish what I was looking for using Microsoft.Extensions.DependencyInjection Container.
In my MSDependencyInjector wrapper class, I used the ActivatorUtilities extension.
public static T GetService<T, I>(I interfaceInstance)
{
return ActivatorUtilities.CreateInstance<T>(container, interfaceInstance);
}
Implemented in my page's partial class I wrote:
_userLoginPresenter = MSDependencyInjector.GetService<UserLoginPresenter,
IUserLoginView>(this);
A Caveat: The 'T' parameter of createInstance wants the concrete class type not the interface. This caused hours of frustration, prompting the creation of this question in the first place. MS documentation isn't the greatest but I definitely misread.
I'm not sure how to implement something as straightforward in Simple Injector and would be interested in knowing. Based on my reading I not sure if my solution isn't something like a service locator, which depending on which camp you are from should be avoided. However, if the implementation of this can be contained for just solving the need for this MVP paradigm then it is my hope all will be well.
I have a code behind page that has several method; one of them is a page method.
[WebMethod]
public static void ResetDate(DateTime TheNewDate)
{
LoadCallHistory(TheNewDate.Date);
}
protected void LoadCallHistory(DateTime TheDate)
{ bunch of stuff }
The method LoadCallHistory works fine when the page loads and I can call it from other methods inside the page. However, in the web method part, it gets underlined in red with the error "an object reference is required for the non-static field".
How do you access functions from the page method part of the code?
Thanks.
You cannot call a non-static method from a static context without having an instance of the class. Either remove static from ResetDate or make LoadCallHistory static.
However, if you remove static from ResetDate you must have an instance of it to use that method. Another approach is to create an instance of the class inside ResetDate and use that instance to call LoadCallHistory, something like this:
[WebMethod]
public static void ResetDate(DateTime TheNewDate)
{
var callHistoryHandler = new Pages_CallHistory();
callHistoryHandler.LoadCallHistory(TheNewDate.Date);
}
The error message indicates that ResetDate has the keyword static and LoadCallHistory does not. When using static either both of the methods needs to be static or the called method needs to be static, the caller cannot be static if the called method is not.
To quote MSDN on "Static Classes and Static Class Members"
A static class is basically the same
as a non-static class, but there is
one difference: a static class cannot
be instantiated. In other words, you
cannot use the new keyword to create a
variable of the class type. Because
there is no instance variable, you
access the members of a static class
by using the class name itself.
Since this is a static method, it can only call other static methods or new objects.
If your page class is CallHistory (educated guess ;)) you will need to do this:
[WebMethod]
public static void ResetDate(DateTime TheNewDate)
{
var thisPage = new CallHistory();
thisPage.LoadCallHistory(TheNewDate.Date);
}
Or change LoadCallHistory to be static.
I'm wondering (based on scoping rules) how I might do the following:
I want to draw to a sprite that exists on the main stage in which I have a class instantiated.
So something like
public function MyClass(reference:String){
this.reference = reference;
}
public function drawToOutsideSprite(){
this.parent.getChildByName(this.reference).addChild(someLoaderName);
}
Would I use super() in this case, or what's the usual methodology?
Thanks,
jml
There are a few ways to do this. I'm assuming your MyClass extends Sprite.
package
{
import flash.display.DisplayObject;
import flash.display.DisplayObjectContainer;
import flash.display.Sprite;
/**
* MyClass
*/
public class MyClass extends Sprite
{
public var referenceA:String;
public var referenceB:Sprite;
public function get referenceA_way2():Sprite
{
return this.parent.getChildByName(referenceA);
}
/**
* MyClass Constructor
*/
public function MyClass(referenceA:String = null, referenceB:Sprite = null)
{
super();
this.referenceA = referenceA;
this.referenceB = referenceB;
}
public function drawToOutsideSpriteA(child:DisplayObject):void
{
// referenceA
this.parent.getChildByName(this.referenceA).addChild(child);
// or
referenceA_way2.addChild(child);
}
public function drawToOutsideSpriteB(child:DisplayObject):void
{
// referenceB
referenceB.addChild(child);
}
public function drawToOutsideSpriteC(referenceC:String, child:DisplayObject):void
{
this.parent.getChildByName(referenceC).addChild(child);
}
// Do this:
// it allows you to abstract out the logic of getting the main sprite
// into some util class, so you could reuse that functionality elsewhere,
// and so your code is cleaner.
public function drawToOutsideSpriteD(child:DisplayObject):void
{
StageUtil.getMainSprite().addChild(child);
}
}
}
package
{
import flash.display.DisplayObject;
import flash.display.DisplayObjectContainer;
import flash.display.Sprite;
/**
* MyClass
*/
public class StageUtil
{
private static var root:Stage;
/**
* Called when app first starts
*/
public static function initialize(stage:Stage):void
{
root = stage;
}
public static function getMainSprite():DisplayObjectContainer
{
return root; // or something more complex,
// like a recursive function to getSpriteByName
}
public static function addToStage(child:DisplayObject):DisplayObject
{
return getMainSprite().addChild(child);
}
}
}
In general I would abstract out the logic for getting the "main" sprite into some util/manager class, because you don't want to hardcode that into your MyClass, as you might need it in other places, and you might want to customize it later on. It sounds like your just asking what's the best way to reference sprites outside of the scope of the MyClass, so I say just put it into the Util, assuming it has good reason for being their (like FlexGlobals.topLevelApplication in Flex, so you can easily access the application).
I don't recommend passing in id's or name's into the constructor and doing it that way, I don't really recommend constructor arguments at all. I would just pass those into a method if you needed to, or have it built into the class itself, or the Util.
To clear up the scoping question a little... You normally don't want to draw to sprites outside the scope of the class you are in, unless they have some special functionality that will be referenced by multiple classes with totally different scopes. This is because things would start not making sense, who's being added to who. But some good examples on when to do thatinclude:
Buttons with ToolTips: Tooltips are added to the root because they appear on top of everything, but a Button could be 20 children deep, so you'd have in the Button subclass, perhaps, addToolTip(child).
PopUps: You might want to add a popup from within MyClass, but it's really being added to the stage. In flex this is like PopUpManager.addPopUp(child), just like the sample StageUtil.getMainSprite().addChild(child). You could even wrap that method so it's like the one in the class above, addToStage.
Transform/Drawing Stage: If you have some global painting stage, or place where you scale/resize things, you might want to be able to add/remove graphics from that from any class.
The super() method isn't useful in this scenario. The only time you really use super() is if you have overridden a method, and want to access the super-classes implementation. Something like this (assuming you're extending Sprite):
override public function addChild(child:DisplayObject):DisplayObject
{
if (child is MyDrawingSprite)
return StageUtil.addToStage(child); // add to main stage
else
return super.addChild(child); // add directly to this class
}
Otherwise, try to stick to just adding children directly to the "MyClass".
Hope that helps.
If I have 2 classes and the first extends the second, how can the second class call a static function from the first?
package p1 {
class a {
static function a1() {
//do soemthing
}
}
class b extends a {
static function b1() {
//do something else
}
}
}
a.a1(); // this works
b.a1(); // this doesn't work
b.b1(); //this works
When "B extends A" - this actually is not the same as "class B has all methods and properties of A". Not class, but object of class B implements all properties and methods, defined in class A. When you call a static method or property - you deal with classes but not objects (it looks very similar to namespaces usage).
ADDED:
The only way solve your task is to override a1(args) in class B and to call super.a1(args) inside... 1 string of code. But it seems to me, that you have a software architect problem if it's not possible to avoid such kind of usage.
Use super to call the parent method.
super.b1();
EDIT: Ok, looking at what you wrote, I think you need to set the scope of a1 to be public or protected.