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What's New in C# 6.0: Dictionary Initializers

I recently did a column about how to create a simple collection class. In that column, I discussed collection initializers which let you add items to a collection when the collection is instantiated. Here's a variation on the example I used in that column which loads two Customer objects into a List:

List<Customer> cList = new List<Customer>() {new Customer("A123"), new Customer("B246") }

Initializers are handy ... right up until you try to use an initializer with a Dictionary. The resulting code is pretty ugly:

Dictionary<string, Customer> cList = new Dictionary<string, Customer>()
{
  {"A123", new Customer("A123")},
  {"B246", new Customer("B246")}
};

Even for C#, that's a lot of punctuation marks in a very small space. C# 6.0 gives you a new syntax that saves a few keystrokes but, more importantly, makes the resulting code easier to read by eliminating some curly braces and leveraging the equals sign. The new syntax looks like this:

Dictionary<string, Customer> cList = new Dictionary<string, Customer>()
{
  ["A123"] = new Customer("A123"),
  ["B246"] = new Customer("B246")
};

That's considerably easier to read.

Posted by Peter Vogel on 04/14/2015 at 2:19 PM


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