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c#constructorthisunirx

the "This" keyword front of constructor parentheses - C#

I know about "This" keyword and what is it working. but what is this using for?

public ReactiveProperty() : this(default(T))
{

}

I have seen this in UniRx Project. I just don't know the "This" keyword front of constructor. I googled it but there is nothing to catch. does anyone know?

Solution

  • This syntax is used to call another constructor defined in the class. Example from the docs:

    class Coords
{
    public Coords() : this(0, 0) // calls Coords(int x, int y) with x = 0 and y = 0
    {  }

    public Coords(int x, int y)
    {
        X = x;
        Y = y;
    }

    public int X { get; set; }
    public int Y { get; set; }

    public override string ToString() => $"({X},{Y})";
}

    var p1 = new Coords();
Console.WriteLine($"Coords #1 at {p1}");
// Output: Coords #1 at (0,0)

var p2 = new Coords(5, 3);
Console.WriteLine($"Coords #2 at {p2}");
// Output: Coords #2 at (5,3)