Question

I’ve a question.
I most recently changed one of my IDictionary to a IEnumerable<KeyValuePair>.
This was made because this collection of items shouldn’t be modified.
As i can see these are the same but IEnumerable dosn’t implement the Add, remove etc, this made this perfect for me and my area of using this collection.

public IDictionary<string, UserInformation> MyItems;
public IEnumerable<KeyValuePair<string, UserInformation>> MyItems;

Now to my questions.

• Is this the smartest way to go if i don’t want the collection to be
  modified?
• Is there a smarter way in doing this?
• Am i being stupid doing like this?

I found simular posts to this before but none actually explaining what to use and why.

Answer 1

The most important problem is that an IDictionary is designed to be used for efficient lookup. If you really only want to represent a sequence of pairs, then your approach is okay – but I wouldn’t use KeyValuePair unless the relationship is really a key/value semantically… in which case I really would just use a dictionary.

You don’t have to expose the dictionary, of course – you can expose methods which only fetch the value for a key (and perhaps also expose a sequence of keys, and a sequence of values).

Or you could create a read-only implementation of IDictionary<,> of course – there’s a sample implementation in this answer.