Cached Property: Easier way?

Question

I have a object with properties that are expensive to compute, so they are only calculated on first access and then cached.

 private List notes;
         


        

Answer 1

If the value is non-trivial to compute, I generally prefer using a method (GetNotes()). There's nothing stopping you from caching the value with a method, plus you can add the [Pure] attribute (.NET 4) if applicable to indicate the method does not alter the state of the object.

If you do decide to stay with the following, I recommend:

Whenever you have a lazily-evaluated property, you should add the following attribute to ensure that running in the debugger behaves the same as running outside of it:

[DebuggerBrowsable(DebuggerBrowsableState.Never)]

Also, starting with .NET 4, you can use the following:

// the actual assignment will go in the constructor.
private readonly Lazy> _notes = new Lazy>(CalcNotes);

[DebuggerBrowsable(DebuggerBrowsableState.Never)]
public List Notes
{
    get { return _notes.Value; }
}