How to Clone Objects

Question

When I do the following.. anything done to Person b modifies Person a (I thought doing this would clone Person b from Person a). I also have NO idea if changing Person a will change Person b after the linking. Due to my code right now, I can only see this in 1 direction.

Person a = new Person() { head = "big", feet = "small" }; Person b = a;   b.head = "small"; //now a.head = "small" too    

Now if I do this instead.. Person a becomes completely separate.

Person b = new Person() { head = a.head, feet = a.feet }; 

Now this fine and kinda makes sense when comparing this behaviour to other things in C#. BUT, this could get very annoying with large objects.

Is there a way to shortcut this at all?

Such as:

Person b = a.Values;

Answer 1

What you are looking is for a Cloning. You will need to Implement IClonable and then do the Cloning.

Example:

class Person() : ICloneable {     public string head;     public string feet;       #region ICloneable Members      public object Clone()     {         return this.MemberwiseClone();     }      #endregion } 

Then You can simply call the Clone method to do a ShallowCopy (In this particular Case also a DeepCopy)

Person a = new Person() { head = "big", feet = "small" }; Person b = (Person) a.Clone();   

You can use the MemberwiseClone method of the Object class to do the cloning.

Answer 2

Is there a way to shortcut this at all?

No, not really. You'll need to make a new instance in order to avoid the original from affecting the "copy". There are a couple of options for this:

1. If your type is a struct, not a class, it will be copied by value (instead of just copying the reference to the instance). This will give it the semantics you're describing, but has many other side effects that tend to be less than desirable, and is not recommended for any mutable type (which this obviously is, or this wouldn't be an issue!)

2. Implement a "cloning" mechanism on your types. This can be ICloneable or even just a constructor that takes an instance and copies values from it.

3. Use reflection, MemberwiseClone, or similar to copy all values across, so you don't have to write the code to do this. This has potential problems, especially if you have fields containing non-simple types.