Nullabe Guid?

I saw this today:

    if (myObject.ResourceValue != null)
    {
        otherData.Value = myObject.ResourceValue.ToString();
    }

and wondered if it is possible to get to this situation. So I tried it out myself and found that you will never have a null, non-nullable guid. See below:

namespace ScratchConsole
{
    public class Haha
    {
        private Guid _value;

        public Guid Null { get { return _value; } }
    }

    public class Program
    {
        static void Main(string[] args)
        {
            Guid? test = null;
            //Guid data = test.Value; // throws an exception.
            //Guid data2 = null; // won't compile
            Guid data3;
            //Console.WriteLine(data3.ToString()); // won't compile, unassigned variable.

            Haha ha = new Haha();

            Console.WriteLine(ha.Null.ToString()); // outputs "00000000-0000-0000-0000-000000000000"
        }
    }
}

It seems that instead you should always check for an empty guid. Like so:

    if (myObject.ResourceValue != Guid.Empty)
    {
        otherData.Value = myObject.ResourceValue.ToString();
    }

Generating TinyUrl Like Id's

I was looking into generating id's for a personal site that I'm doing for fun. The first thing I did was Google around a bit to see what other people are doing. There were some pretty good ideas out there, most of them taking a url and hashing it to a Base64 representation.

That was fine and dandy, but the methods they were using were long and hideous. I'm a huge fan of short and simple approaches because odds are, it's already been done by Microsoft. Since everyone was talking about hashing I figured I would see what this was about in my search result. How to Hash Passswords

It was still a little too complicated. I knew there had to be something simpler. Then I realized that on the Path object you can generate a temporary file name. It's pretty short. I tried it out and it was exactly what I was looking for! I just had to chop off the portion I wanted, since I wanted to restrict it to 7-8 characters.

Dictionaries and Hashtables

I see Hashtable being used everywhere it seems. Hashtable is a early data structure in c#, this was pre-.net 2.0.

Ideally we should avoid using Hashtable where possible because thanks to generics, Dictionary, is more efficient. This is because Dictionary does not have to box and unbox the values. If you're not familiar with this you can reference this article. http://msdn.microsoft.com/en-us/libr...=vs.80%29.aspx Dictionary is also a type safe way of storing and retrieving data and therefore should be preferred so as to avoid experiencing run time errors.

There are actually multiple types of dictionaries available:

1. ConcurrentDictionary - thread safe (can be safely accessed from several threads concurrently)
2. HybridDictionary - optimized performance (for few items and also for many items)
3. OrderedDictionary - values can be accessed via int index (by order in which items were added)
4. SortedDictionary - items automatically sorted by key
5. StringDictionary - strongly typed and optimized for strings

There are other data structures out there in c# that can be really effective. I highly recommend you read this article multiple times when you get the chance. It's a little dated (.Net 2.0) http://msdn.microsoft.com/en-us/libr...1%28v=vs.80%29 But it's really good and dives deep into how each of the core data structures work.

One of the engineers I work with pointed out something else that's pretty awesome. KeyedCollection, here's what he had to say:

The KeyedCollection uses a Dictionary internally. It is another nice way of managing keyed data.

http://msdn.microsoft.com/en-us/library/ms132438.aspx

http://stackoverflow.com/questions/7...eyedcollection