This is a constraint on the generic parameter of your class, meaning that any type that is passed as the generic type must have a parameterless constructor.
So,
public class C : B
{
public C() {}
}
would be a valid type. You could create a new instance of A<C>.
However,
public class D : B
{
public D(int something) {}
}
would not satisfy the constraint, and you would not be allowed to create a new instance of A<D>. If you also added a parameterless constructor to D, then it would again be valid.
Best Answer
This is a constraint on the generic parameter of your class, meaning that any type that is passed as the generic type must have a parameterless constructor.
So,
would be a valid type. You could create a new instance of
A<C>
.However,
would not satisfy the constraint, and you would not be allowed to create a new instance of
A<D>
. If you also added a parameterless constructor to D, then it would again be valid.