#610 – Lazy Evaluation in Property Get Accessors

One of the benefits in using a property in a class, rather than a public field, is that you can delay calculation of the property’s value until client code actually tries to read the value.

In the code below, we define a FullDogDescription property that is read-only.  The private backing variable is initialized to an empty string and we only calculate its value in the get accessor when someone tries to read the property’s value.

<pre>        private string fullDogDescription = "";
        public string FullDogDescription
                // Generate full description the first time that
                // someone reads this property.
                if (fullDogDescription == "")
                    fullDogDescription = GenerateDogDescription();

                return fullDogDescription;

The benefit of doing this is that if the call to GenerateDogDescription takes some time, we don’t spend the time calculating a value until some piece of code actually needs a value.


About Sean
Software developer in the Twin Cities area, passionate about software development and sailing.

One Response to #610 – Lazy Evaluation in Property Get Accessors

  1. Mikhail says:

    I prefer to write such code as one-liner:

    private string fullDogDescription = null;

    public string FullDogDescription
    get { return fullDogDescription ?? ( fullDogDescription = GenerateDogDescription() ); }

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