Variable class properties due to specific constructor in C#

Question

Suppose class A as:

public class A
{
    private string _str;
    private int _int;

    public A(string str)
    {
        this._str = str;
    }

    public A(int num)
    {
        this._int = num;
    }

    public int Num
    {
        get
        {
            return this._int;
        }
    }

    public string Str
    {
        get
        {
            return this._str;
        }
    }
}

I want to hide Str property when i construct class A as

new A(2)

and want to hide Num property when i construct class A as

new A("car").

What should i do?

You should say what your use case is, and then decide on an appropriate design for that use case. What you ask for is not only impossible but also goes against basic OO principles. — Jon
– Jon, Commented Jan 24, 2013 at 10:59

Marc Gravell · Accepted Answer · 2013-01-24 10:59:41Z

8

That isn't possible with a single class. An A is an A, and has the same properties - regardless of how it is constructed.

You could have 2 subclasses of abstract A, and a factory method...

public abstract class A
{
    class A_Impl<T> : A
    {
        private T val;
        public A_Impl(T val) { this.val = val; }
        public T Value { get { return val; } }
    }
    public static A Create(int i) { return new A_Impl<int>(i); }
    public static A Create(string str) { return new A_Impl<string>(str); }
}

But : the caller will not know about the value unless they cast it.

answered Jan 24, 2013 at 10:59

Marc Gravell

1.1m273 gold badges2.6k silver badges3k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

sanchop22 Over a year ago

Would you give an example or suggest an article regarding to this issue?

Marc Gravell Over a year ago

@petre well, I've added some code, but fundamentally you are trying to do something that is contrary to object orientation

Hossein Narimani Rad · Accepted Answer · 2013-01-24 11:01:21Z

2

use generics

public class A<T>
{
    private T _value;

    public A(T value)
    {
        this._value= value;
    }

    public TValue
    {
        get
        {
            return this._value;
        }
    }
}

answered Jan 24, 2013 at 11:01

Hossein Narimani Rad

32.7k19 gold badges92 silver badges121 bronze badges

1 Comment

Robert Fricke Over a year ago

although this would also enable new A(DateTime.Now)for example, meaning the constructor takes any type.

Collectives™ on Stack Overflow

Variable class properties due to specific constructor in C#

2 Answers 2

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related