Can interfaces inherit c

Add by applying the overload resolution rules of Overload resolution. Similarly the invocation n. Add 1. When explicit casts are inserted, there is only one candidate method, and thus no ambiguity. F member is hidden by the ILeft. F member.

The invocation d. F 1 thus selects ILeft. F , even though IBase. F appears to not be hidden in the access path that leads through IRight. The intuitive rule for hiding in multiple-inheritance interfaces is simply this: If a member is hidden in any access path, it is hidden in all access paths. An interface member is sometimes referred to by its fully qualified name. The fully qualified name of an interface member consists of the name of the interface in which the member is declared, followed by a dot, followed by the name of the member.

The fully qualified name of a member references the interface in which the member is declared. For example, given the declarations. In the example above, it is not possible to refer to Paint as ITextBox. When an interface is part of a namespace, the fully qualified name of an interface member includes the namespace name.

For example. Here, the fully qualified name of the Clone method is System. Interfaces may be implemented by classes and structs. To indicate that a class or struct directly implements an interface, the interface identifier is included in the base class list of the class or struct. For example:. A class or struct that directly implements an interface also directly implements all of the interface's base interfaces implicitly.

This is true even if the class or struct doesn't explicitly list all base interfaces in the base class list. When a class C directly implements an interface, all classes derived from C also implement the interface implicitly. The base interfaces specified in a class declaration can be constructed interface types Constructed types.

A base interface cannot be a type parameter on its own, though it can involve the type parameters that are in scope. The following code illustrates how a class can implement and extend constructed types:. The base interfaces of a generic class declaration must satisfy the uniqueness rule described in Uniqueness of implemented interfaces.

For purposes of implementing interfaces, a class or struct may declare explicit interface member implementations. An explicit interface member implementation is a method, property, event, or indexer declaration that references a fully qualified interface member name. Add are explicit interface member implementations. In some cases, the name of an interface member may not be appropriate for the implementing class, in which case the interface member may be implemented using explicit interface member implementation.

A class implementing a file abstraction, for example, would likely implement a Close member function that has the effect of releasing the file resource, and implement the Dispose method of the IDisposable interface using explicit interface member implementation:.

It is not possible to access an explicit interface member implementation through its fully qualified name in a method invocation, property access, or indexer access. An explicit interface member implementation can only be accessed through an interface instance, and is in that case referenced simply by its member name.

It is a compile-time error for an explicit interface member implementation to include access modifiers, and it is a compile-time error to include the modifiers abstract , virtual , override , or static.

Explicit interface member implementations have different accessibility characteristics than other members. Because explicit interface member implementations are never accessible through their fully qualified name in a method invocation or a property access, they are in a sense private. However, since they can be accessed through an interface instance, they are in a sense also public. For an explicit interface member implementation to be valid, the class or struct must name an interface in its base class list that contains a member whose fully qualified name, type, and parameter types exactly match those of the explicit interface member implementation.

Thus, in the following class. CompareTo results in a compile-time error because IComparable is not listed in the base class list of Shape and is not a base interface of ICloneable. Likewise, in the declarations. Clone in Ellipse results in a compile-time error because ICloneable is not explicitly listed in the base class list of Ellipse.

The fully qualified name of an interface member must reference the interface in which the member was declared. Thus, in the declarations. The interfaces implemented by a generic type declaration must remain unique for all possible constructed types.

Without this rule, it would be impossible to determine the correct method to call for certain constructed types. For example, suppose a generic class declaration were permitted to be written as follows:.

Were this permitted, it would be impossible to determine which code to execute in the following case:. To determine if the interface list of a generic type declaration is valid, the following steps are performed:.

The declaration is invalid because any constructed type with U and V being the same type would cause these two interfaces to be identical types. The code. When a generic method implicitly implements an interface method, the constraints given for each method type parameter must be equivalent in both declarations after any interface type parameters are replaced with the appropriate type arguments , where method type parameters are identified by ordinal positions, left to right.

When a generic method explicitly implements an interface method, however, no constraints are allowed on the implementing method. Instead, the constraints are inherited from the interface method.

The method C. In this case, C. The constraint for method C. Omitting the constraint would also be an error since constraints of implicit interface method implementations are required to match. WriteLine "Implement method 3" ;. Output: Implement method 1 Implement method 2 Implement method 3. Output: Total number of votes is: Name of the author is: Siya Total number of published article is: Previous C Multiple inheritance using interfaces.

Next C How to use Interface References. Recommended Articles. Article Contributed By :. Easy Normal Medium Hard Expert. And to the comments below. Jordan, also note that the base class and the list of interfaces being inherited are separated by commas after the initial colon Mehrdad's example. Adding the implementation explicitly does not impact the base class, but it can help put emphasis on the interface.

David, while you're not wrong, it wasn't terminology that was preventing Jordan's code from working. It was incorrect syntax. Show 2 more comments. David M David M 69k 13 13 gold badges silver badges bronze badges. Or Eric Lippert, whose writing is very accurate. I had a discussion with another developer about whether or not interfaces "inherit", "implement", "require", or "bring along" interfaces with a declaration like: public interface ITwo : IOne The technical answer is that ITwo does inherit IOne for a few reasons: Interfaces never have an implementation, so arguing that ITwo implements IOne is flat wrong ITwo inherits IOne methods, if MethodOne exists on IOne then it is also accesible from ITwo.

Though, unfortunately, interfaces inherit other interfaces. I find that choice of words unfortunate, but we're stuck with it now.

I prefer to think of interfaces as requiring other interfaces. Eric I agree it's an unclear term and debated it with a colleague a while back. In the end we decided that saying "ITwo inherits IOne".

I'll update my answer with a couple small reasons just because they won't fit clearly in a comment. Sure; if you define "A inherits from B" as meaning "members of B are all members of A", then interfaces do "inherit" from base interfaces. This is a reasonable definition. But I prefer to think of "inheritance" as being more strictly about not just sharing the abstract, unimplemented members, but rather, being about inheriting implementations.

Since interfaces have no implementations, I find it somewhat disquieting to think of interfaces as inheriting from anything. It's a subtle and debatable point. I came across a new requirement that will require an enum to be needed by many of the classes that implement Interface A , but not all the classes need this enum.

I don't want the classes that don't require this new enum to implement this new functionality. So I created interface B that contains the new enum that I needed to add. I then made interface B inherit interface A and this is my concern, Is it ok for one interface to Inherit another interface? To continue with my changes, I then changed the classes that needed the new enum to implement interface B instead of interface A since it was inherited by interface B.

I thought about implementing both interfaces in my classes that needed them but I'm using the interface throughout the code and would like to just use one interface for looking through classes and not two. I hope this was clear enough probably too long but if anyone can give me some advice on this either I'm doing it right or I'm doing it wrong please let me know.

Interface inheritance is an excellent tool, though you should only use it when interface B is truly substitutable for interface A, not just to aggregate loosely-related behaviors. It's difficult to tell whether it is appropriate for your specific case, but there's nothing wrong using the practice in principle. You see it in the first-rate APIs all the time. To pick just one common example, from the. NET framework:.

Consider whether the interfaces should be logically paired, and if you feel that they work well with each other then absolutely use inheritance. Printers and scanners are often separate objects, each with their own functionality however these two devices are often paired in the same device;. It makes sense that IPhotocopier should inherit from IScanner and IPrinter as this now allows the photocopier to be used as either a scanner or printer which it contains in addition to its primary roll as a copier.

It would not make sense to allow IBlender to be inherited by any of the earlier interfaces what would you call them? If you can't give your new interface a sensible name this might indicate that your may not want to use inheritance in this instance. It's a bad idea to inherit some interfaces such as IDisposable, since this forces all implementations of your new interface to implement the dispose pattern even if they do not have any disposable resources. Technically speaking, interfaces don't inherit from each other.

In this example, the IFoo interface does not have a DoBar method.