Extending Hashtable - is there a better way? [modified]

[Clive D Pottinger]

Hello everyone. Some time ago, I was working with Hashtables when I found a limitation: as an example I will use the following:

Hashtable countryInfo = new HashTable();
countryInfo.Add("Canada", "Ottawa");
countryInfo.Add("UK", "London");
countryInfo.Add("France", "Paris");
...

This is great: given the country France, I can find out that it's capital is Paris:

string capital = countryInfo["France"]

What I can't do is find out is what country is Paris the capital of (without looping through the table). So I created MultiHashTable which, instead of holding key,value pairs, holds key,key,key... sets. I can now do things like:

MultiHashTable countryInfo = new MultiHashTable("Country", "Capital", MultiHashTable.Unkeyed("Language"));
countryInfo.Add("Canada", "Ottawa", "English");
countryInfo.Add("UK", "London", "English");
countryInfo.Add("France", "Paris", "French");

(note: the "Language" table is "Unkeyed" because it must hold duplicate entries for Canada and UK). Now I can find out what country has Paris as it's capital:

capital = countryInfo.GetItem("Country", "Capital", "Paris");

and other things that I needed to do. My question is this - did I re-invent the wheel? I keep discovering all kinds of stuff already built into C# and I can't help but think that this sort of thing is already in there somewhere. I won't consider my time wasted if it is - creating MultiHashTable was a great learning experience - I just want to know if at some time in the future someone is going to say "well why don't you just use System.Collections.SuperCrossRef like everybody else?"

Clive Pottinger Victoria, BC

modified on Wednesday, January 23, 2008 1:42:53 PM

[engsrini]

Iam not sure what version you are working on, i think this can be done with Dictionary(.net 2.0), Please take a look at it. Thanks Srini