Why is an Add method required for { } initialization?

Question

To use initialization syntax like this:

var contacts = new ContactList
{
    { \"Dan\", \"dan.tao@email.com\" },
    { \"Eric\", \"ceo@google.com\" }
};
<         


        

Answer 1

Collection initializers are expressions, so they can be used where only expression are valid, such as a field initializer or LINQ query. This makes their existence very useful.

I also think the curly-bracketed { } kind of initialization, smells more like a fixed size collection, but it's just a syntax choice.

Answer 2

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.

Answer 3

I'd love to have the initializer syntax for immutable types(both collections and normal types). I think this could be implemented with a special constructor overload using a syntax similar to params.

For example something like this:

MyClass(initializer KeyValuePair<K,V>[] initialValues)

But unfortunately the C# team didn't implement such a thing yet :(

So we need to use a workaround like

MyClass(new KeyValuePair<K,V>[]{...})

for now