Params IEnumerable c#

Question

Why cant I use an IEnumerable with params? Will this ever be fixed? I really wish they would rewrite the old libraries to use generics...

Answer 1

Ah, I think I may now have understood what you mean. I think you want to be able to declare a method like this:

public void Foo(params IEnumerable items)
{
}

And then be able to call it with a "normal" argument like this:

IEnumerable existingEnumerable = ...;
Foo(existingEnumerable);

or with multiple parameters like this:

Foo("first", "second", "third");

Is that what you're after? (Noting that you'd want the first form to use T=string, rather than T=IEnumerable with a single element...)

If so, I agree it could be useful - but it's easy enough to have:

public void Foo(params T[] items)
{
    Foo((IEnumerable) items);
}

public void Foo(IEnumerable items)
{
}

I don't find I do this often enough to make the above a particularly ugly workaround.

Note that when calling the above code, you'll want to explicitly specify the type argument, to avoid the compiler preferring the params example. So for example:

List x = new List();
Foo(x);