Multiple input types in C# property setter

Question

I have a property that looks like this:

private int clientID;

    public int ClientID
    {
        get { return clientID; }
        set { clientID = value; }
    }

I would like to be able to pass in a string to this property so that the setter will convert it for me. How do I do that?

I know how to do the conversion, I just need to know how to pass in a string without it throwing a type error.

Answer 1

You can't, basically. Options:

• Have a second property for the ClientID as text (backed by the same field)
• Have a separate method (e.g. SetClientID(string))
• Change the property type to object and do different things based on the value passed in (urgh - please don't do this!)

Answer 2

You cannot. You can create a method like this though

public void SetClientId(string clientId)
{
    this.ClientID = Convert.ToInt32(clientId);
}

Answer 3

You can't pass a string to a property which is declared as integer. You could use a method instead.

Answer 4

I recommend you don't try. You're only causing headaches for a later date.

Add an additional setter, instead...

public string ClientIDText
{
    set
    {
        clientID = int.Parse(value);
    }
}

or create a SetClientID(string) method.

There is an advantage to create a SetClientID method; you can create overloads, so you could create

SetClientID(int)
SetClientID(string)
etc.

However, I still think you're building ambiguity into your app for the convenience of saving a few lines of code.

Answer 5

Alternatively, you can provide a ClientID class that has implicit conversion between itself, int and string, then you can have a property:

public ClientIdType ClientId
{
    get; set;
}

But all the callers could then use it thus:

var myClass = new MyClass();
myClass.ClientId = 1;
myClass.ClientId = "2";

int id = myClass.ClientId;

http://msdn.microsoft.com/en-us/library/85w54y0a.aspx

However, this seems like a lot of legwork just to make it easier for the caller, but it's still an option.

Answer 6

I think the cleanest solution is, as some others have suggested is to create a ClientId class. I don't think this is necessarily bad, as this post explains in a pretty good way:

Many classes have a tendency to consume or expose primitive values like integers and strings. While such primitive types exist on any platform, they tend to lead to procedural code. Furthermore they often break encapsulation by allowing invalid values to be assigned.

Having a seperate class gives you different sorts of possibilities to validate the the id as well, if that is a requirement. In the end, it is all about encapsulation.

Something like this should get you started:

//auto-property for your class
public ClientId ClientID
{
   get; set;
}

And the ClientId class:

public class ClientId
{
  private int _id;

  public ClientId(int id) { _id = id; }
  public ClientId(string id) { //convert id to int, throw exception if invalid }

  public int Value { return _id; }
}

Don't forget to implement Equals and GetHashCode as well, which can be done trivially for this class.

Answer 7

How about as an alternative in the property:

    private int rowValue_;
    public object RowValue
    {
        get
        {
            return this.rowValue_;
        }
        set
        {
            var type = value.GetType();
            if (type == typeof(string))
            {
                this.rowValue_ = Convert.ToInt32(value);
            }
            else if (type == typeof(int))
            {
                this.rowValue_ = (int)value;
            }
            else
            {
                throw new InvalidDataException(
                    "HandwritingData RowValue can only be string or int. 
                    Passed in parameter is typeof {0}",
                    value.GetType().ToString());
            }
        }
    }

It works for me as well as trapping bad parameters.

Regards, Chris

Answer 8

In this example How Can I inherit the string class? there is a nice contribution by René if you can stand having a property not being a pure string - but serve as one and be able to cast:

class Foo {
    readonly string _value;
    public Foo(string value) {
        this._value = value;
    }
    public static implicit operator string(Foo d) {
        return d.ToString();
    }
    public static implicit operator Foo(string d) {
        return new Foo(d);
    }
}

Answer 9

You can't overload properties, so that won't work.

What you can do is

1. Just convert the thing to an int before setting it (preferred)
2. Create a method to do the conversion from clients, i.e., SetClientIdFromString(strign id ).