Abstract property with public getter, define private setter in concrete class possible?
Solution 1
Unfortunately, you can't do exactly what you want. You can do this with interfaces though:
public interface IInterface {
string MyProperty { get; }
}
public class Class : IInterface {
public string MyProperty { get; set; }
}
The way I would do it is to have a separate SetProperty method in the concrete classes:
public abstract class AbstractClass {
public abstract string Value { get; }
}
public class ConcreteClass : AbstractClass {
private string m_Value;
public override string Value {
get { return m_Value; }
}
public void SetValue(string value) {
m_Value = value;
}
}
Solution 2
Found a solution: How to override a getter-only property with a setter in C#?
public abstract class A
{
public abstract int X { get; }
}
public class B : A
{
public override int X { get { return 0; } }
}
/*public class C : B //won't compile: can't override with setter
{
private int _x;
public override int X { get { return _x; } set { _x = value; } }
}*/
public abstract class C : B //abstract intermediate layer
{
public sealed override int X { get { return this.XGetter; } }
protected abstract int XGetter { get; }
}
public class D : C //does same thing, but will compile
{
private int _x;
protected sealed override int XGetter { get { return this.X; } }
public new virtual int X { get { return this._x; } set { this._x = value; } }
}
D
is now equivalent to a class inheriting from B
while also being able to override in a setter.
Solution 3
You can just use protected
access modifier instead. Because of inheritance you are not allowed to use private
. It looks like so:
public abstract class A
{
public abstract int prop { get; protected set; }
}
public abstract class B : A
{
public override int prop { get; protected set; }
}
comecme
Updated on September 09, 2020Comments
-
comecme over 3 years
I'm trying to create an abstract class that defines a property with a getter. I want to leave it up to derived classes to decide if they want to implement a setter for the property or not. Is this possible?
What I have so far:
public abstract class AbstractClass { public abstract string Value { get; } public void DoSomething() { Console.WriteLine(Value); } } public class ConcreteClass1 : AbstractClass { public override string Value { get; set; } } public class ConcreteClass2 : AbstractClass { private string _value; public override string Value { get { return _value; } } public string Value { set { _value = value; } } } public class ConcreteClass3 : AbstractClass { private string _value; public override string Value { get { return _value; } } public void set_Value(string value) { _value = value; } }
In
ConcreteClass1
, I get an error on theset
. It can't overrideset_Value
because no overridable set accessor exists in AbstractClass.In
ConcreteClass2
, I get an error on bothValue
's because a member with the same name is already declared.ConcreteClass3
doesn't give an error, but even though Value's set accessor would be compiled into set_Value, it doesn't work the other way around. Defining aset_Value
does not mean thatValue
gets a set accessor. So I can't assign a value to a ConcreteClass3.Value property. I can use ConcreteClass3.set_Value("value"), but that's not what I'm trying to achieve here.Is it possible to have the abstract class demand a public getter, while allowing an optional setter to be defined in a derived class?
In case you'r wondering, this is just a theoretical question. I don't have a real situation where something like this is needed. But I can imagine an abstract class that doesn't care how a property gets set, but that does need to be able to get the property.