Question

I am new in C#, going from PHP. Everything is almost clear, except I don’t know what exactly means construction Interface/Collection <>.

I am already using the <> for “type definition”, but what it means exactly. I am using it like this:

class TaskComparer : IEqualityComparer<Task> ...
class TaskQueue : ConcurrentQueue<Task> ...

etc. Did you see any article about this? Please post a link. Thank you.

Answer 1

It’s called “Generics”, and it’s a way to (as you say) define a type parameter. Here’s an introductory article on MSDN: http://msdn.microsoft.com/en-us/library/ms172192.aspx

As a simple example of the utility of this, think about a Repository pattern.

public interface IRepository<T> {
    public void Add (T obj);
    public IEnumerable<T> GetAll();
}

With the correct implementation, now you can have a repository interface for any type of entity.

public void someMethod(IRepository<Person> personsRepo) 
{
    IEnumerable<Person> persons = personsRepo.GetAll();
    // ...
}