What's the false operator in C# good for?

Question

There are two weird operators in C#:

• the true operator
• the false operator

If I understand this right these operators can be used in typ

Answer 1

You can use it to override the && and || operators.

The && and || operators can't be overridden, but if you override |, &, true and false in exactly the right way the compiler will call | and & when you write || and &&.

For example, look at this code (from http://ayende.com/blog/1574/nhibernate-criteria-api-operator-overloading - where I found out about this trick; archived version by @BiggsTRC):

public static AbstractCriterion operator &(AbstractCriterion lhs, AbstractCriterion rhs)
{
       return new AndExpression(lhs, rhs);
}

public static AbstractCriterion operator |(AbstractCriterion lhs, AbstractCriterion rhs)
{
       return new OrExpression(lhs, rhs);
}

public static bool operator false(AbstractCriterion criteria)
{
       return false;
}
public static bool operator true(AbstractCriterion criteria)
{
       return false;
}

This is obviously a side effect and not the way it's intended to be used, but it is useful.