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...
public Point2D(Point2D point) : this(point.X, point.Y) { }
Point2D is a value type. If it's a class it may be null.
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;
}
Maybe your class isn't quite complete. Personally, I use a private init() function with all of my overloaded constructors.
class Point2D {
double X, Y;
public Point2D(double x, double y) {
init(x, y);
}
public Point2D(Point2D point) {
if (point == null)
throw new ArgumentNullException("point");
init(point.X, point.Y);
}
void init(double x, double y) {
// ... Contracts ...
X = x;
Y = y;
}
}