Replace Dictionary with an Insertion Perserving Collection

[nickbabcock]

ReadDictionary returns a Dictionary, as one might expect. There is only one problem with this function and it is inherently tied to the return type. A Dictionary doesn't preserve insertion order. Ordinarily this isn't a problem, but what if the client of this library wants to write a dictionary in the same order that it was read. This is impossible.

So many times I've run into data like

flags={
    flag_a=1402.3.21
    flag_b=1403.2.1
    [...]
}

It feels wrong to create a class or action to define how to parse this when the functionality is already in the parser.

I'm unsure what the solution is. Ideally, the IDictionary<TKey, TValue> return type should be kept, but I'm not sure if that will be possible. My only idea involves creating a custom type with a dictionary and a list. The only time the list would come into play would be when GetEnumerator was called (so, whenever the client calls foreach on the collection). This kinda seems like a lot of overhead for something simple.

The alternative solution is to change the interface from IDictionary<TKey, TValue> to IList<KeyValuePair<TKey, TValue>> and make the client responsible for dictionary creation if they need it. If this route is taken, I would prefer the method to be renamed to something like ReadKeyValues

[Measter]

Why not use an OrderedDictionary?

[nickbabcock]

If only it was generic, it would be perfect.

[TommasoBelluzzo]

http://www.codeproject.com/Articles/18615/OrderedDictionary-T-A-generic-implementation-of-IO

[nickbabcock]

Thanks for the link! I think I would have to dig into it a lot more to see what the performance trade offs would be and if they'd be worth it. I've also had success using Tuple<string, 'T>[], so I'm not sure it's critical for this issue to be implemented.