C#•12mo ago

Can this be implemented?

Hello, I'd like to implement an interface that meets the following conditions. Is it possible?

1. that interface can inherited class that inherit class A.
2. that interface cannot inherited class that inherit interface B.

1. that interface can inherited class that inherit class A.
2. that interface cannot inherited class that inherit interface B.

14 Replies

Angius•12mo ago

Interfaces cannot inherit classes, so no Classes can implement interfaces Interfaces can implement other interfaces Classes can inherit from other classes

class Foo : IFoo {} // yes
class Foo : Bar {} // yes
interface IFoo : IBar {} // yes
interface IFoo : Foo {} // no

class Foo : IFoo {} // yes
class Foo : Bar {} // yes
interface IFoo : IBar {} // yes
interface IFoo : Foo {} // no

! 휘백OP•12mo ago

I misinterpreted. So, is this possible? There are class A, interfaces B, C, and D B can only inherit A or objects that inherit A. In other words, classes that do not inherit A cannot inherit B. C can't be inherited like D. In other words, it's impossible to inherit C and D together in any class.

Angius•12mo ago

Again, interfaces cannot inherit classes

interface IBar {}
class Foo : IBar {} // class Foo implements interface IBar

interface IBar {}
class Foo : IBar {} // class Foo implements interface IBar

class Foo {}
class Bar : Foo {} // class Bar inherits from class Foo

class Foo {}
class Bar : Foo {} // class Bar inherits from class Foo

interface IFoo {}
interface IBar : IFoo {} // interface IBar implements interface IFoo

interface IFoo {}
interface IBar : IFoo {} // interface IBar implements interface IFoo

This is what you can do Additionally, a class can implement many interfaces And an interface can implement many interfaces But a class can only ever inherit from one class

cap5lut•12mo ago

it's impossible to inherit C and D together in any class

u can not have such constraints with interfaces if u want such constraints u have to fiddle around to get a specific class hierarchy, as only with classes u can somewhat limit inheritance like that whats the actual use case here?

Thinker•12mo ago

You could do this using a generic constraint, but again what's the use-case?

cap5lut•12mo ago

u cant constrain with generics either that something does not implement an interface or am i missing something here?

Thinker•12mo ago

If you wanted an interface which implementing classes have to inherit another class you could do interface IA<T> where T : B, IA<T>, and if B doesn't inherit anything else then you're indirectly restricting the inheritance chain. But this is less useful as you have to use generics to pass instances of the interface

cap5lut•12mo ago

i was actually talking about the "can not implement both interfaces at the same time" thingy

Thinker•12mo ago

ah yeah can't do that

! 휘백OP•12mo ago

Okay, okay, I think the translator is weird, so I'll just give you an example and explain it

class A {}

interface B {}
interface C {}
interface D {}
...
class SA : A, B {} //I want it work
class OT : O, B {} //I want it don't work

class SC : C {} //Work
class SD : D {} //Work
class SCD : C, D {} //Don't work

class A {}

interface B {}
interface C {}
interface D {}
...
class SA : A, B {} //I want it work
class OT : O, B {} //I want it don't work

class SC : C {} //Work
class SD : D {} //Work
class SCD : C, D {} //Don't work

Can I do like that?

cap5lut•12mo ago

its impossible to disallow a class to implement a certain interface

Дядя Женя•12mo ago

https://learn.microsoft.com/en-us/previous-versions/dotnet/netframework-4.0/x4yx82e6(v=vs.100)?redirectedfrom=MSDN

Inheritance Demands

Дядя Женя•12mo ago

But what you're trying to do is really unnecessary and hard to achieve, drop it

Gax•12mo ago

What would even be the use case for that

Gaming

Programming

Can this be implemented?