Ruby and Rails have several methods for creating a new object that looks like another: clone, dup, deep_dup. When using them you should be aware of their differences so that you can select the method you really need.

`clone`

Shallow copy: references to other objects/values are copied (instead of cloning those objects/values)
Clones the object and all its "special object attributes" like frozen, tainted and modules that the object has been extended with
Ruby 2.6 documentation for clone Show archive.org snapshot

`dup`

Shallow copy: references to other objects/values are copied (instead of cloning those objects/values)
Clones the object, but ignores "special object attributes" like frozen, tainted and modules that the object has been extended with
Ruby 2.6 documentation for dup Show archive.org snapshot

`deep_dup`

Provided by ActiveSupport
"Special object attributes" like frozen, tainted and singleton methods are ignored (like dup)
Behavior depends on implementation
- Hash Show archive.org snapshot : returns a deep copy, i.e. referenced objects/values will be deep_duped as well
- Array Show archive.org snapshot : returns a new array where each object is deep_duped
- any other Object Show archive.org snapshot : calls dup, or self when frozen. If your object has instance variables that are hashes or arrays, those will not be deep_duped.

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Ruby / Rails: clone vs. dup vs. deep_dup

`clone`

`dup`

`deep_dup`

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