Get change commands without modifying collection

Probably a very poorly named title, but anyway...

I am using the command pattern on a hierarchical data set. So basically I need a method that returns an object that describes the changes that will be made without actually changing the data. So for example:

Object 1 -> Object 2 -> Object 3

If I move object 1, it will cause a change in Object 2, which will cause a change in Object 3 because they depend on each other. So...I need a method to recursively go through the hierarchical collection and gather up the changes that are required to move Object 1 without actually modifying the collection. Halfway through the recursion it would be nice to be able to use something like Object1.Location, but it may already slated for change so I can't reliably use it.

I feel like there are plenty of algorithms and such that need to do this type of "in place" modification. As a non-CS major I didn't learn much of this type of thing, so I don't really even know what search terms to look for to find a "solution". I put solution in quotes because I realize there probably isn't a direct solution for my开发者_运维知识库 problem, but I am merely looking for some good guidelines/examples of this being done to get my brain cranking.

Can anyone provide some real-world examples of this type of thing being done? Thanks in advance.

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Well part of the solution might be the visitor pattern. You can go through your object tree with the visitor and do something like generating a "cloned" tree representing what will be the result of what you want to do ...

Can you give us an example of what you want to achieve ?

my2c