#592 – Optional Parameters in Indexers

In addition to defining optional parameters within methods, you can also include an optional parameter in an indexer.

For example, assume that we have a Dog class that keeps track of the sounds that a dog makes when he barks and that we’ve defined an indexer for the class that retrieves a “bark sound” from that list.

        public string this[int i]
        {
            get
            {
                return BarkRecord[i];
            }
        }

Using the indexer:

            kirby.Bark("Woof");
            kirby.Bark("Bow-wow");
            kirby.Bark("Urgh");

            Console.WriteLine(kirby[2]);


We can now add an optional parameter to the indexer, to indicate that we’d like the date/time of the bark returned as well.

        public string this[int i, bool includeTime = false]
        {
            get
            {
                string barkInfo = BarkRecord[i];

                if (includeTime)
                    barkInfo = barkInfo + string.Format(" at {0}", BarkTime[i]);

                return barkInfo;
            }
        }

Using the indexer:

            Console.WriteLine("Bark at [2]={0}", kirby[2]);
            Console.WriteLine("Bark at [1]={0}", kirby[1, true]);

Advertisements

About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: