c# - How to have access to instance members in a static method?

Question

I'm trying to create classes to encapsulate validation and logic for objects like Email , URL , phone number and so on . in the first try I found that I'm repeating the same code in all classes specially static IsValid and the Constructor . so I decided to create a base class to put all the same codes in it . so there is a base class that other classes inherit it . it's abstract as I don't want it to be used directly .

public abstract class BaseClass
{
            protected string value;
            private bool isValid;

            public bool IsValid{get { return this.isValid;}}

    protected virtual string RegexPattern{get;}

    protected virtual RegexOptions RegexOption{get;}

    private BaseClase(){}

    protected BaseClass(string value)
    {
        this.isValid = Validator.IsValid(value , RegexPattern, RegexOption);
        this.value = this.isValid ? value : string.Empty;
    }

    public static bool Validate(string value)
    {
        return Validator.IsValid(value ,RegexPattern, RegexOption); // rror
    }

}

public class Email
{
    private override string RegexPattern
    {
        get
        {
            return ".*";
        }
    }

    private override RegexOptions RegexOption
    {
        get
        {
            return RegexOptions.SingleLine;
        }
    }

            public string Address{get {return this.value; }}

    public Email(string address) : base(address){}
}

the problem is with the static IsValid method of BaseClass . in the current code it throws errors as RegexPattern and RegexOption are instance members . I don't want to defined the same value twice for instance and static methods . it works if I use

const string RegexPattern= ".*";
const RegexOptions RegexOption =RegexOptions.SingleLine;

but I need to be able to override these values in sub classes so this is not applicable . and as I have defined the BaseClass as abstract I cant instantiate it inside static method to have access to properties .

and as I want to use static method just like Email.IsValid("foo@bar.com"); , I don't know how to pass an instance through it .

so , how can I have access to RegexOption and RegexPattern in this static method ?

Answer 1

so , how can I have access to PropOne and PropTwo in this static method ?

You need to have an instance somehow, otherwise it's a meaningless operation. So the question is - how would you want to identify the instance that you're interested in? Do you really need Validate to be static at all?

Note that instead of having abstract properties, if you expect the values to always stay the same throughout an instance of the class, you might want to make the values part of the constructor for BaseClass instead, and just keep them in fields.

If what you're trying to achieve is that each subclass has a single separate validator, I would separate the two concerns - give each subclass a static property of a different type. You wouldn't be able to call this polymorphically, but it sounds like you don't really want to anyway.

We can't really tell what your classes are meant to represent here - if you can give us more concrete context, we can probably be more helpful.