Decompiling the New C# 14 field Keyword

Summary

Properties in C# are a powerful tool for encapsulating data inside a class. They let you specify getter and setter logic that’s automatically applied when reading from or writing to the property. They’ve been supported since C# 1.0, which required manual backing fields for storage. C# 3.0 then introduced auto-implemented properties to remove these boilerplate backing fields. However, it came with a trade-off: if you needed custom logic in your get or set method, you still had to use a manual backing field.C# 14 introduces the new field keyword, which combines the flexibility of a manual backing field with the simplicity of an auto-implemented property. In the sections that follow, you'll see how the compiler handles this new keyword in practice. We'll also cover some important caveats to keep in mind as you start using it.A Brief Overview of the field KeywordBefore C# 14, backing fields were necessary whenever a property needed logic beyond just retrieving and setting a field value. The snippet below demonstrates how a manual backing field is required for the Email property, since it cleans up the incoming value before storing it:public class User { // Auto-property: simple getter and setter public string Name { get; set; } // Field-backed property: more complex getter and setter private string _email; public string Email { get => _email; set => _email = value.Trim().ToLower(); } public User(string name, string email) { Name = name; Email = email; } }Auto-implemented properties are convenient for simple scenarios, but as shown above, they fall short when you attempt to add custom logic. The new field keyword in C# 14 fills this gap. It lets you keep your code concise, while still allowing for custom logic in your property accessors.The above snippet can be simplified in C# 14 as follows: public class User { public string Name { get; set; } - private string _email; public string Email { - get => _email; + get; - set => _email = value.Trim().ToLower(); + set => field ...