Inheriting Constructors?

Question

Is it possible to inherit constructors, and if so, how? I am trying to make a class that inherits a System class, and I want the constructors of it.

Answer 1

This is not possible in vanilla C#. Constructors can't be simply inheritted. They must be redefined on every level and then chained to the parent's version.

class Parent { 
  internal Parent(string str) { ... }
  internal Parent(int i) { ... }
}

class Child : Parent {
  internal Child(string str) : base(str) { ... }
  internal Child(int i) : base(i) { ... }
}

Answer 2

Constructors don't 'inherit' the same way that methods do, but you do have the option of invoking base class constructors:

public DerivedClass(Foo foo) : base(foo)

Answer 3

All the other answers so far are correct. However, understand that you do not have to match the base class constructor's signature with the constructor you are defining:

public class Base
{
   public Base(string theString) { ... }
}

public class Derived:Base
{
   public Derived():base("defaultValue") //perfectly valid
   { ... }
   public Derived(string theString)
      :base(theString)
   { ... }
   public Derived(string theString, Other otherInstance)
      :base(theString) //also perfectly valid
   { ... }
}

... and in addition to invoking a parent class's constructor, you can also "overload" constructors within the same inheritance level, by using the this keyword:

public class FurtherDerived:Derived
{
   public FurtherDerived(string theString, Other otherInstance)
      :base(theString, otherInstance)
   { ... }

   public FurtherDerived()
      :this("defaultValue", new Other()) //invokes the above constructor
   { ... }
}

Answer 4

You can't inherit constructors; you have to call them explicitly (except for the default constructor, which is called, well, by default):

class A
{
    public A (int i) { }
}

class B : A
{
    public B (int i) : base (i) { }
}