使用 null 合并运算符“??”将自动实现的属性分配给自身

Question

I have an auto-implemented property which takes the default value. This property reads its value from a database, but if that's null it should take its default value.

    // Variable Declaration
    public bool IsSoundEffects { get; set; } = true;

    // Usage
    bool? readFromDB = null;    // Get it from Database assume its NULL
    IsSoundEffects = readFromDB ?? IsSoundEffects;

Is assigning IsSoundEffects to itself a usual practice if a previous database read results in null?

What should do the trick to make this code organized and readable?

Answer 1

What you are doing is fine. As an alternative, GetValueOrDefault will also work.

IsSoundEffects = readFromDb.GetValueOrDefault(IsSoundEffects);

Either of these are good solutions if your readFromDb was really a method with parameters because you can have clean syntax such as the below

IsSoundEffects = readFromDb(some, parameters).GetValueOrDefault(IsSoundEffects);
IsSoundEffects = readFromDb(some, parameters) ?? IsSoundEffects;

The former was your only option prior to the ?? operator being introduced into C#.

If the "assign to self" is distasteful, then avoid the initial assignment, and do it explicitly elsewhere, eg

public bool IsSoundEffects { get; set; }
...
IsSoundEffects = readFromDb(some, parameters).GetValueOrDefault(true);
IsSoundEffects = readFromDb(some, parameters) ?? true;

Answer 2

Make it simple

if(readFromDB != null) IsSoundEffects = readFromDB;

So that you can avoid the assignment of same value when readFromDB is null.