I suspect that I'm missing something stupid, so feel free to blast me, but:
I'm reading through Test Driven Development: By Example and one of the examples is bugging me. In chapter 3 (Equality for all), the author creates an equals function in the Dollar class to compare two Dollar objects:
public boolean equals(Object object)
{
Dollar dollar= (Dollar) object;
return amount == dollar.amount;
}
Then, in the following chapter (4: Privacy), he makes amount a private member of the dollar class.
private int amount;
and the tests pass. Shouldn't this cause a compiler error in the equals method because while the object can access its own amount member, it is restricted from accessing the other Dollar object's amount member?
//shouldn't dollar.amount be no longer accessable?
return amount == dollar.amount
Am I fundamentally misunderstanding private?
UPDATE I decided to go back and code along with the book manually and when I got to the next part (chapter 6 - Equality For All, Redux) where they push amount into a parent class and make it protected, I'm getting access problems:
public class Money
{
protected int amount;
}
public class Dollar : Money
{
public Dollar(int amount)
{
this.amount = amount;
}
// override object.Equals
public override bool Equals(object obj)
{
Money dollar = (Money)obj;
//"error CS1540: Cannot access protected member 'Money.amount'
// via a qualifier of type 'Money'; the qualifier must be of
// type 'Dollar' (or derived from it)" on the next line:
return amount == dollar.amount;
}
}
Does this mean that protected IS instance-based in C#?