Static property issue

Question

1.00/5 (2 votes)

See more:

public abstract class A
    {
        public static string f { get; set; }
    }

    public class B : A {
        static B()
        {
            f = "B";
        }
    }

    public class C : A
    {
        static C()
        {
            f = "C";
        }
    }

What I have tried:

C c = new C();
B b = new B();
The result is:
C.f is B
B.f is B
A.f is B

what i expect is:
C.f is C
B.f is B
A.f is NULL

How to implement this using static property?

Posted 21-Sep-18 6:01am

855

Updated 21-Sep-18 21:32pm

Add a Solution

3 solutions

Solution 1

f is static: there is one of it for the whole application. Because both B and C are derived from A, they share the same static variable: the last value to you set it to will be the global value it has, regardless of whether you set it via an instance of B or C

So which ever instance you create most recently defines the value of f .

Posted 21-Sep-18 6:45am

OriginalGriff

v2

Solution 4

A static member is the same for every instance of the class and its derived children.
The solution you found completely defeats the point of having a static property.
Why do you think you need the property to be static, if it can be different for every child class?

Edit: example implementation.

C#

public abstract class A
{
   public string F { get; protected set; }
}

public class B : A
{
   public B()
   {
      F = "B Class";
   }
}

public class C : A
{
   public C()
   {
      F = "C Class";
   }
}

Hope this helps.

Posted 21-Sep-18 21:33pm

phil.o

Updated 24-Sep-18 11:51am

v2

Comments

855 22-Sep-18 14:13pm

Say i have a Product class which has a ProductType field. And two child class, mouse and keyboard which ProductType is mouse or keyboard. So the ProductType can be used in the scope of each child class.

phil.o 22-Sep-18 22:49pm

But that does not mean that the ProductType property has to be static :)

855 23-Sep-18 11:32am

my goal is to share the ProductType in each child class.
In this scenario, do you have other suggestions? thanks.

phil.o 24-Sep-18 17:45pm

Just leave the property as non static in the base class. In child classes' constructors, just assign the desired value.
You can make the property's accessor public for the get and protected for the set; this way, it will be publicly readable on instances of the classes, but only writeable from the child classes implementations.
I updated my solution to give you a quick example.

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

855 · Accepted Answer · 2018-09-21T20:16:00

i found a solution of this:

C#

public abstract class A
{
    public static string f { get; set; }
}


public class B : A 
{
    public new static string f { get; set; }

    static B()
    {
        f = "B";
    }
}

public class C : A
{
    public new static string f { get; set; } 

    static C()
    {
        f = "C";
    }
}