C#

static void SomeMethod(Base instance) {
    instance.Name();
}

mschuckmann wrote:

The wayI understood the where statement is that I'm telling it to accept objects derived from type Base or that have the same interface as type Base.

mschuckmann wrote:

within a Generic you lose all static type information

mschuckmann wrote:

a generic is no better than a class or method that takes a common ancestor class

Luc Pattyn wrote:

That is not correct: you dont loose all information, both the Generic method and the
SomeMethod method accept Base objects or Base derivatives, and these objects keep their characteristics.

Luc Pattyn wrote:

It is only the way you define your classes (thru the virtual/override/new keywords)
that decides whether you get the functionality of the base method or the more specialized
method. That has nothing to do with generics.

Luc Pattyn wrote:

That is correct if you use where T : type.
But generics can be used without type constraint (acting somewhat like C++ templates).
And they can be used with more complex constraints; read up on "where" in MSDN for that.

mschuckmann wrote:

If you leave out the where constraint you've essentially specified a generic with a constraint of object and you can't call any methods except those declared by object. Therefore my example code will not compile without the where constraint. So sure you can impliment generics without type constraints but don't expect to do anything interesting in your generic code.

interface Named
{
	void Name();
};

class Base : Named
{
	public void Name()
	{
		Console.WriteLine("I'm a Base class");
	}
};

class Middle : Base, Named
{
	public new void Name()
	{
		Console.Write("I'm a Middle class");
	}
};

class Child : Middle, Named
{
	public new void Name()
	{
		Console.Write("I'm a Child class");
	}
};

class Program
{
	static void PrintName<T>( T instance ) where T : Named
	{
		instance.Name();
	}

	static void Main( string[] args )
	{
		Child c = new Child();
		PrintName( c );
		Console.ReadLine();
	}
}