Question

Just a thought.

Wouldn’t it be useful to have optional type parameters in C#?

This would make life simpler. I’m tired of having multiple classes with the same name, but different type parameters. Also VS doesn’t support this very vell (file names) 🙂

This would for example eliminate the need for a non-generic IEnumerable:

interface IEnumerable<out T=object>{
  IEnumerator<T> GetEnumerator()
}

What do you think?

Answer 1

I am definitely for it.

I’m currently writing helper methods for different scenarios where I want to pass references to different members and methods of classes. To accomplish this I’m taking, for example, an Expression<Func<TIn, TOut>> as argument to the helper (that lets me reach the method with a lambda expression, thus keeping everything strongly typed).

BUT – I currently need to define a new helper method for each different number of input arguments, since I need to have a different amount of generic arguments to it. Instead of

HelperMethod<TIn>(Expression<Action<TIn>> arg) // Yes, C# can distinguish
HelperMethod<TOut>(Expression<Func<TOut>> arg) // these two from eachother
HelperMethod<TIn, TOut>(Expression<Func<TIn, TOut>> arg)
HelperMethod<TIn1, TIn2, TOut>(Expression<Func<TIn1, TIn2, TOut>> arg)
// etc

I could make do with, at the most, two methods:

HelperMethod<TIn>(Expression<Action<TIn>> arg)
HelperMethod<TOut, TIn1 = DummyType, ...>(Expression<Func<TIn1, ..., TOut> arg)

In my case, it would avoid a lot of code duplication…