How can I force the base constructor to be called in C#?

Question

I have a BasePage class which all other pages derive from:

public class BasePage

This BasePage has a constructor which contains code which must always run:

public BasePage()
{
    // Important code here
}

I want to force derived classes to call the base constructor, like so:

public MyPage
    : base()
{
    // Page specific code here
}

How can I enforce this (preferably at compile time)?

Answer 1

The base constructor will always be called at some point. If you call this(...) instead of base(...) then that calls into another constructor in the same class - which again will have to either call yet another sibling constructor or a parent constructor. Sooner or later you will always get to a constructor which either calls base(...) explicitly or implicitly calls a parameterless constructor of the base class.

See this article for more about constructor chaining, including the execution points of the various bits (such as variable initializers).

Answer 2

The base class constructor taking no arguments is automatically run if you don't call any other base class constructor taking arguments explicitly.