Question

To use initialization syntax like this:

var contacts = new ContactList
{
    { "Dan", "[e-mail]" },
    { "Eric", "[e-mail]" }
};

…my understanding is that my ContactList type would need to define an Add method that takes two string parameters:

public void Add(string name, string email);

What’s a bit confusing to me about this is that the { } initializer syntax seems most useful when creating read-only or fixed-size collections. After all it is meant to mimic the initialization syntax for an array, right? (OK, so arrays are not read-only; but they are fixed size.) And naturally it can only be used when the collection’s contents are known (at least the number of elements) at compile-time.

So it would almost seem that the main requirement for using this collection initializer syntax (having an Add method and therefore a mutable collection) is at odds with the typical case in which it would be most useful.

I’m sure I haven’t put as much thought into this matter as the C# design team; it just seems that there could have been different rules for this syntax that would have meshed better with its typical usage scenarios.

Am I way off base here? Is the desire to use the { } syntax to initialize fixed-size collections not as common as I think? What other factors might have influenced the formulation of the requirements for this syntax that I’m simply not thinking of?

Answer 1

The reason for this is that it was retrofitted. I agree with you that using a constructor taking a collection would make vastly more sense, but not all of the existing collection classes implemented this and the change should (1) work with all existing collections, (2) not change the existing classes in any way.

It’s a compromise.