Question

In my application development, I concluded that I need this variable.

IDictionary<string, IDictionary<Levels, IList<Problem>>> PackageDictionaryForProblems
IDictionary<string, IDictionary<Levels, IList<ProblemRule>>> PackageDictionaryForProblemRules

But as I need to access to each key of the dictionary, so it’s a pain. I supposed that would be a good option create a class to avoid write all the datatype:

public class PackageDictionaryForProblems : IDictionary<string, IDictionary<Levels, IList<Problem>>>
{ }

// the sane for the second dictionary

What do you think about this? Is a good practice to create just this class? Or should I need to create several classes for each one? I.E.

public class ProblemCollection : IList<Problem>
{ }

Answer 1

There is no difference at runtype between the two options of defining multi-level collections like

IDictionary<string, IDictionary<Levels, IList<Problem>>> PackageDictionaryForProblems

or defining/using a type like

public class PackageDictionaryForProblems : IDictionary<string, IDictionary<Levels,     IList<Problem>>>
{ }

Without any further functionality in PackageDictionaryForProblems, it simply serves as an alias for IDictionary<string, IDictionary<Levels, IList<Problem>>>.

You still end up with the same memory allocation, access times, etc. Adding that custom type only simplifies readability of your code (or not… personally I find it easier to look at the IDictionary<string, IDictionary<Levels, IList<Problem>>> definition to understand the data structure. That’s just personal preference).