CODEWITHSUNDEEP
c#interface
VolkanUzun
VolkanUzun

Reputation: 188

setter for a property not defined in the interface

If my interface has the signature only for getter such as:

public interface IInterface 
{
   object Id{get;}
}

So the interface only dictates a public getter for Id on any implemented class now when i have the class :

public class Simple : IInterface
{
  object Id
  {
    get{return something;} 
    set{ do something else;}
  }
}

the compiler complains about the setter as the setter is not defined in the interface. However I didnt dictate anything on the interface contract for a setter; why does the interface insist on the setter on the derived classes ?

Upvotes: 2

Views: 764

Answers (2)

supercat
supercat

Reputation: 81159

In designing .net, Microsoft decided to make there be three non-interchangeable types of properties: read-only, write-only, and read-write. In C#, if one declares a read-write property with the same name as one or more interface properties one is supposed to implement, the compiler can automatically create not only the read-write property the programmer actually specified, but read-only and/or write-only properties as needed to satisfy the interfaces. For example, if interface IReadableFoo implements a read-only property Foo, IWritableFoo implements a write-only property Foo, and IReadWriteFoo inherits IReadableFoo and IWritablefoo, and implements a "new" read-write property Foo, and a class ReadWriteFoo implements IReadWriteFoo and declares a public read-write property Foo, the compiler will have ReadWriteFoo generate interface implementations of read-only property IReadableFoo.Foo, write-only property IWritableFoo.Foo, and read-write property IReadWriteFoo.Foo.

Upvotes: 1

Reed Copsey
Reed Copsey

Reputation: 564413

You just need to make Id public. For example, this compiles fine:

public interface IInterface
{
    object Id { get; }
}
public class Simple : IInterface
{
    private int something;
    public object Id
    {
        get { return something; }
        set{ something = (int)value;}
    }
}

Upvotes: 11

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