Object Initializers in

About Object Initializers

Object initializers are an alternative to constructors. The syntax is a comma separated list of field name=value pairs, illustrated below:

public class Person
{
    public string Name;
    public string Address;
}

var person = new Person{Name="The President", Address = "Élysée Palace"};

Collections can also be initialized in this way. Typically, this is accomplished with comma separated lists as shown here:

IList<Person> people = new List<Person>{ new Person(), new Person{Name="Joe Shmo"}};

This approach (and syntax) can be used with any class that implements IEnumerable and has an Add() method.

Fields can be listed in any order or ommitted completely.

Dictionaries use the following syntax:

IDictionary<int, string> numbers = new Dictionary<int, string>{ [0] = "zero", [1] = "one"...};

// or

IDictionary<int, string> numbers = new Dictionary<int, string>{ {0, "zero" }, {1,  "one"}...};

The initialized fields must be accessible to the caller. Typically, this means they must be public or internal.

There is a strong trend promoting immutability amongst the language designers and leading practitioners, so the mutability of objects initialized in this way is seen as a disadvantage. There are proposals to introduce an init clause in the upcoming version of the language, C# 9, which may address this.

• object initializer documentation describes how to use initialzers.
• collection initializer documentation gives a preview of how initializers can be used with collections like dictionaries and lists.