C# – Public Fields versus Automatic Properties

automatic-propertiescclassfieldproperties

We're often told we should protect encapsulation by making getter and setter methods (properties in C#) for class fields, instead of exposing the fields to the outside world.

But there are many times when a field is just there to hold a value and doesn't require any computation to get or set. For these we would all do this number:

public class Book
{
    private string _title;

    public string Title
    {
          get => _title; 
          set => _title = value;
    }
}

Well, I have a confession, I couldn't bear writing all that (really, it wasn't having to write it, it was having to look at it), so I went rogue and used public fields.

Then along comes C# 3.0 and I see they added automatic properties:

public class Book
{
    public string Title { get; set; } 
}

Which is tidier, and I'm thankful for it, but really, what's so different than just making a public field?

public class Book
{
    public string Title;
}

Best Answer

In a related question I had some time ago, there was a link to a posting on Jeff's blog, explaining some differences.

Properties vs. Public Variables

  • Reflection works differently on variables vs. properties, so if you rely on reflection, it's easier to use all properties.
  • You can't databind against a variable.

  • Changing a variable to a property is a breaking change. For example: 

    TryGetTitle(out book.Title); // requires a variable
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