This keyword in some case not clear

Question

when I doing a coding I come across a function like this =>

public RelayCommand(Action<object> execute): this(execute, null)

I really dont know about the "this" key word usage here

`this` in that context usually means call another constructor of *this* class with these arguments. It is a way of reducing code duplication — Hunter McMillen, May 09 '13 at 03:29

score 5 · Answer 1 · answered May 09 '13 at 03:29

It's constructor chaining. this(execute, null) calls another constructor defined in that class which takes an Action<object> and some other value. For example:

class Whatever
{
    public Whatever() : this("string arg") {}  // calls Whatever(string)

    public Whatever(string something) {}
}

score 1 · Answer 2 · answered May 09 '13 at 03:29

This particular use of this keyword lets you call one constructor from the other, presumably to supply a default argument. You can "fold" both constructors into one by applying default parameter values:

public RelayCommand(Action<object> execute, string name = null) {
    ...
}

score 0 · Answer 3 · answered May 09 '13 at 03:30

0

This is referring to an overloaded version of the current constructor. Basically the two constructors are chained together which can be good for avoiding duplicate code in constructors

answered May 09 '13 at 03:30

TGH

38,769
12
102
135

This keyword in some case not clear

3 Answers3