C# 6 Features: Dictionary Initializers

October 27, 2016 - .NET, C#, Programming

This is part of a series of posts covering new C# 6 features. Currently there are posts covering the following:
String Interpolation
Expression-bodied Members
Improved Overload resolution
The Null Conditional operator
Auto-Property Initializers

Yet another new feature introduced into C# 6 are a feature called Dictionary Initializers. These are another “syntax sugar” feature that shortens code and makes it more readable- or, arguably, less readable if you aren’t familiar with the feature.

Let’s say we have a Dictionary of countries, indexed by an abbreviation. We might create it like so:

This is the standard approach to initializing dictionaries as used in previous versions, at least, when you want to initialize them at compile time. C#6 adds “dictionary initializers” which attempt to simplify this:

Here we see what is effectively a series of assignments to the standard this[] operator. It’s usually called a Dictionary Initializer, but realistically it can be used to initialize any class that has a indexed property like this. For example, it can be used to construct “sparse” lists which have many empty entries without a bunch of commas:

The “Dictionary Initializer” which seems more aptly referred to as the Indexing initializer, is a very useful and delicious syntax sugar that can help make code easier to understand and read.

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