C# 6 Feature Review: Auto-Property Enhancements

With the release of Visual Studio 2015 came the (final) release of the Roslyn C# compiler and C# 6. This latest version of C#’s feature list seems to be…less than exciting, but it’s important to keep in mind that before Roslyn, none of these new features would have ever made it into a release. It was simply too hard to add a feature in C#, so higher impact/value features made it in while minor annoyances/enhancements would be deferred, indefinitely.

I’m less concerned about the new features themselves than how these features would actually enhance my code. With ReSharper, it’s pretty easy to see what the impact of these new features would be.

In this series, I’ll be looking at a long-lived codebase, AutoMapper, and walk through features of C#, their potential utility/impact, and when you should use them. First up are the auto-property enhancements.

Initializers for auto-properties

The auto-property enhancements mainly center around making fields and properties on an even playing field. In a lot of my AutoMapper code, I have field initializers:

Property initializers would instead look like this:

It looks…rather strange to me. The only place in my code where I could find that I could use property auto-property initializers were places I had existing private fields in place. And I’m not terribly keen on converting private fields into private properties. Properties are my window into exposing state to the others, otherwise I use private fields to encapsulate state. And no I’m not one of those weirdos that leaves off access modifiers, waaaaaay too easy to screw up.

Verdict: Use sparingly

Getter-only automatic properties

One pattern I found all over the place in AutoMapper are immutable properties. In C# 5 and earlier, this involved creating a private readonly field and a get-only property. I have this all over the place:

Not *horrible* but it would be nice to encapsulate the idiom of an immutable property in the language. This is exactly what getter-only automatic properties do:

I’m only allowed to set the property in a constructor or initializer, and cannot set it anywhere else inside or outside my class. It has the same effect as a readonly field, just encapsulated. I use this pattern now all over the place.

Verdict: Adopt immediately and replace obsolete pattern

AutoMapper 4.1.0 Released