C# constructors overloading

Question

How I can use constructors in C# like this:

public Point2D(double x, double y) {     // ... Contracts ...      X = x;     Y = y; }  public Point2D(Point2D point) {     if (point == null)         ArgumentNullException("point");     Contract.EndContractsBlock();      this(point.X, point.Y); } 

I need it to not copy code from another constructor...

Answer 1

public Point2D(Point2D point) : this(point.X, point.Y) { } 

Answer 2

You can factor out your common logic to a private method, for example called Initialize that gets called from both constructors.

Due to the fact that you want to perform argument validation you cannot resort to constructor chaining.

Example:

public Point2D(double x, double y) {     // Contracts      Initialize(x, y); }  public Point2D(Point2D point) {     if (point == null)         throw new ArgumentNullException("point");      // Contracts      Initialize(point.X, point.Y); }  private void Initialize(double x, double y) {     X = x;     Y = y; }