C# Lazy Loaded Automatic Properties

Question

In C#,

Is there a way to turn an automatic property into a lazy loaded automatic property with a specified default value?

Essentially, I am trying to turn this...

private string _SomeVariable  public string SomeVariable {      get      {           if(_SomeVariable == null)           {              _SomeVariable = SomeClass.IOnlyWantToCallYouOnce();           }            return _SomeVariable;      } } 

into something different, where I can specify the default and it handles the rest automatically...

[SetUsing(SomeClass.IOnlyWantToCallYouOnce())] public string SomeVariable {get; private set;} 

Answer 1

No there is not. Auto-implemented properties only function to implement the most basic of properties: backing field with getter and setter. It doesn't support this type of customization.

However you can use the 4.0 Lazy<T> type to create this pattern

private Lazy<string> _someVariable =new Lazy<string>(SomeClass.IOnlyWantToCallYouOnce); public string SomeVariable => _someVariable.Value; 

This code will lazily calculate the value of _someVariable the first time the Value expression is called. It will only be calculated once and will cache the value for future uses of the Value property

Answer 2

Probably the most concise you can get is to use the null-coalescing operator:

get { return _SomeVariable ?? (_SomeVariable = SomeClass.IOnlyWantToCallYouOnce()); }