CODEWITHSUNDEEP
c#.net
xWoundwortx
xWoundwortx

Reputation: 5

How to assign class instances in exception handler during constructor execution

    public Alphabet(params char[] list)
    {
        this.ExceptionInitializer();
        try
        {
            if (list != null) _alphabet = list;
            else throw this.NullableAssignment; //add exception handler;
            this._charCounter = list.Length;
        }
        catch (this.NullableAssignment)
        {
          //  var x = new Alphabet();   
          //  this = x;      //FAIL!
        }
    }

Upvotes: 0

Views: 100

Answers (5)

CARLOS LOTH
CARLOS LOTH

Reputation: 4745

The code you are proposing is not valid in C#, you cannot assign any value to this. What you could do is to use a call to a default constructor like this:

public Alphabet() { /* Do some default initialization here */ }

public Alphabet(params char[] list) : this() // The call to the default constructor.
{ 
    if (list != null) 
    {
        _alphabet = list; 
        this._charCounter = list.Length; 
    }
}

Upvotes: 2

ICR
ICR

Reputation: 14162

public Alphabet() {
    ConstructEmptyAlphabet();
}

public Alphabet(char[] list) {
    if (list == null) {
        ConstructEmptyAlphabet();
    } else {
        _alphabet = list;
        this._charCounter = list.Length;
    }
}

private void ConstructEmptyAlphabet() {
    …
}

Upvotes: 0

Matthew Flaschen
Matthew Flaschen

Reputation: 284796

I don't know what you're trying to do. Can you show ExceptionInitializer and NullableAssignment? Do you want to assign an empty array to _alphabet when no parameters are passed in?

public Alphabet(params char[] list)
{
    if(list != null)
    {
        _alphabet = list;
    }
    else
    {
        _alphabet = new char[0];
    }
    this._charCounter = _alphabet.Length;
}

This will work for any number of arguments, or an explicit null:

new Alphabet('f', 'o', 'o')
new Alphabet()
new Alphabet(null)

Upvotes: 0

Lee
Lee

Reputation: 144136

You can't do this - the closest thing would be to create a static factory method which returns an Alphabet:

public class Alphabet
{
    private Alphabet(params char[] list)
    {
         //setup
    }

    public static Alphabet Create(params char[] list)
    {
        return list == null
            ? new Alphabet()
            : new Alphabet(list);
    }
}

Although given your example, even simpler would just be to assign an empty array in the place of null:

public Alphabet(params char[] list)
{
    _alphabet = list ?? new char[] { };
    this._charCounter = _alphabet.Length;
}

Upvotes: 0

JSBձոգչ
JSBձոգչ

Reputation: 41378

I'm guessing that you want the constructor for Alphabet to process the elements of list, unless list is empty in which case a special "empty object" should be used. This, unfortunately, can't be accomplished using a normal constructor. What you need instead is a factory method:

private static Alphabet _emptyAlphabet = new Alphabet();
private Alphabet(char[] list) { /* etc */ }

public Alphabet CreateAlphabet(params char[] list)
{
    if (list == null)
    {
        return _emptyAlphabet;
    }
    else
    {
        return new Alphabet(list);
    }
}

Upvotes: 0

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