为什么引用类型变量的行为类似于值类型变量

Question

So, I have a reference type which is Weapon:

class Weapon
{
    //Some properties that are both value type and reference type
}

And I have another class to hold an array of weapons and fire an event when the current weapon changes:

class WeaponManager
{
    Weapon[] weapons;
    Weapon currentWeapon;

    Weapon CurrentWeapon
    {
       get => currentWeapon;
       set
       {
           Weapon oldWeapon = currentWeapon;
           currentWeapon = value;
           OnWeaponChanged?.Invoke(oldWeapon, currentWeapon);
       }
    }
}

I declare the oldWeapon variable and assign it to currentWeapon in order to hold the data. My question is that I believe since the Weapon is a reference type, when I reassign currentWeapon, oldWeapon should also change. But for some reason assignements I make to currentWeapon variable doesn't effect the oldWeapon. Is there some sort of thing going around that I'm not aware of or did I misunderstand something?

Note: Weapon class is deriving from another class which has at least one string in it but I'm not sure if that's the issue.

Answer 1

There is something going on that you're not misunderstanding. Each reference you establish to an object in memory is its own reference, it is not a reference to another reference to the object (it is not a chain)

//if you do
currentWeapon = "a sword"
oldWeapon = currentWeapon

//then you have this
oldWeapon --> "a sword" <-- currentWeapon

//you do not have this
oldWeapon  --> currentWeapon --> "a sword"


//if you then do this
currentWeapon = "a gun"

//then you have this
oldWeapon --> "a sword"      currentWeapon --> "a gun"

//you do not have this
oldWeapon  --> currentWeapon --> "a gun"