sealed

问题 I need to raise an event when the value of the property is changed. In my case this is when webView.Source is changed. I can't make a derived class because the class is marked as sealed. Is there any way to raise an event ? Thank you. 回答1: Raise event when property is changed For this scenario, you could create a DependencyPropertyWatcher to detect DependencyProperty changed event. The follow is tool class that you could use directly. public class DependencyPropertyWatcher<T> :

问题 While inspecting the the .net object model in the Object Browser window, I came across the lack of information on sealed classes. If for instance, one navigates to the mscorlib container -> System namespace -> String class, the details pane displays the following: public class String Member of System Summary: Represents text as a series of Unicode characters. Attributes: [System.Runtime.InteropServices.ComVisibleAttribute(true), System.Reflection.DefaultMemberAttribute("Chars")] It seems I

问题 I'm wondering how the following code is optimized. Specifically concerning virtual and direct calls. I have commented on how I think everything is optimized but those are just guesses. public abstract class Super { public abstract void Foo(); public void FooUser() { Foo(); } } public class Child1 : Super { public override void Foo() { //doSomething } } public class SealedChild : Super { public override void Foo() { //doSomething } } class Program { void main() { Child1 child1 = new Child1();

问题 I am using classes from a dll in my C++ project. All is working fine, until... When trying to call a certain method (listed in the object browser), I am getting an error that this method is not a member of the namespace. Upon investigation, I noticed that this method is listed as "virtual void x() sealed". Is there a way to make a call to such a function? 回答1: For future reference, I just received a response from the enterprise library support team. They posted a link to the following:

问题 Today im working in WPF. I tried to inherit from System.Windows.Shapes.Line class, like this: class MyLine : System.Windows.Shapes.Line { public Ln() { this.Stroke = Brushes.Black; } } I just realized, that Line class is sealed. My goal is to create a class, that will work like Line class (to put it on Canvas ), but I don't want to mess my code with adding brush to it everytime, lets say always want black brush/stroke with 2px width. I feel im trying to do it wrong. How should I do that? 回答1:

问题 I'm currently using an XMLSerializer to serialize a list of a class of my own. One of the class's properties is an instance of a sealed class that does not have a parameterless constructor, so the XML Serializer refuses to serialize the class. How can I get around this? I need that property to be serialized. Is there some way for me to specify how that class should be serialized? We'd like to stay with XML; is there another XML serializer that I could use that would not have this problem?

问题 I'm trying to implement a method in a super class that should be available for use, but not changeable, in sub classes. Consider this: export abstract class BaseClass { universalBehavior(): void { doStuff(); // Do some universal stuff the same way in all sub classes specializedBehavior(); // Delegate specialized stuff to sub classes } protected abstract specializedBehavior(): void; } My intention would be that any sub class of BaseClass would not only be free to omit implementation of

问题 Is it always necessary to follow the sealed keyword with override in the signature of a method like the below code: public sealed override string Method1(){.....} I mean, if I want to "seal" the method within the base class without overriding, is the override keyword still necessary? 回答1: Sealing a method only makes sense if you override it. What happens here is the following: You are overriding a method from a base class ( override ) and tell the compiler that classes derived from your class

问题 This question really is kinda pointless, but I'm just curious: This: public sealed class MyClass { protected void MyMethod(){} } compiles, but gives a warning while This: public sealed class MyClass { public virtual void MyMethod(){} } doesn't compile. Just out of sheer curiosity, is there a reason for this? 回答1: The only reason I can think of is that sometimes you would need to write protected methods to override other protected methods. The language could have been designed to allow this:

问题 I want to make a type that can be inherited from by types in the same assembly, but cannot be inherited from outside of the assembly. I do want the type to be visible outside of the assembly. Is this possible? 回答1: You can make the constructor internal: public class MyClass { internal MyClass() { } } Every class that derives from a base class must call a constructor of the base class in its constructor. Since it can't call the constructor if the base class is in a different assembly, the