Deep copy
A deep copy is an independent duplicate of a data structure that recursively copies its nested objects rather than sharing mutable contents with the original.
100 C++ Mistakes and How to Avoid Them
Deep copy semantics create independent copies of dynamically owned or referenced resources rather than sharing the same resource.
- How it is used
- Preserves class invariants when copying objects that own dynamic resources or other resources that must not be shared.
- How deep it goes
- Explains shallow copying, independent allocation, cleanup before assignment, and the big 3/5, but stops short of general ownership design.
- Examples
- Uses Page and TextSection pointers, communication channels with queued messages, limited printers, and std::unique_ptr implementations.
- What you can do after
- Build it from scratch by implementing independent copies, safe assignment cleanup, destruction, and modern move operations.
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Grokking Simplicity
A deep copy recursively duplicates a data structure and all nested objects and arrays so that no structural parts are shared with the original.
- How it is used
- Protects immutable data when it crosses boundaries into or out of code that may mutate it.
- How deep it goes
- Defines recursive structural duplication and compares its cost with shallow copying, but defers a robust JavaScript implementation.
- Examples
- Uses a shopping cart, web API JSON exchanges, and Erlang or Elixir process messages as defensive-copying examples.
- What you can do after
- Apply it via Lodash’s _.cloneDeep() when robust JavaScript deep copying is required.
Elixir in Action, Third Edition
A deep copy is a recursive copy of a value that duplicates the complete hierarchy of nested terms rather than sharing its mutable parts.
- How it is used
- Explains how BEAM processes exchange data while preserving shared-nothing isolation.
- How deep it goes
- Explains message and closure copying, performance trade-offs, reference exceptions, and ETS snapshots without detailing the copy algorithm.
- Examples
- Uses spawned closures, process messages, and ETS reads and writes as concrete copying boundaries.
- What you can do after
- Evaluate data-transfer costs and isolation behavior when designing concurrent BEAM processes or using ETS.
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Python How-To
A deep copy is a copied object whose interior objects are recursively copied so that mutable objects are not shared with the original.
- How it is used
- Supports independently editing copied task data without changing the original.
- How deep it goes
- Explains recursive copying through mutable task tags and contrasts it with shallow copying, while deferring customized behavior to a challenge.
- Examples
- Uses a Task object whose copied tags list gains "red" while the original tags remain unchanged.
- What you can do after
- Apply it via copy.deepcopy to create independently editable object graphs.
The Quick Python Book, Fourth Edition
A deep copy is a recursively independent copy of a container and the modifiable objects nested within it.
- How it is used
- Protects original nested data when copied lists or dictionaries must be modified independently.
- How deep it goes
- Explains shallow references, demonstrates nested mutations, and stops short of implementation internals.
- Examples
- Demonstrates nested lists, slicing, copy.deepcopy, and mutations through shallow and deep copies.
- What you can do after
- Apply it via Python's copy module to isolate nested mutable objects before changing copied data.
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Related concepts
- shallow copycontrasts with · A shallow copy duplicates a data structure’s outer container while retaining references to its nested values rather than copying them recursively.
- defensive copyused by · A defensive copy is an independently created duplicate of mutable data that prevents subsequent external modifications from affecting retained state.
- copycontrasts with · Copying is the creation of a separate representation of an existing value, object, or data, preserving some or all of its contents or state.
- copy assignment operatorused by · A copy assignment operator is a C++ special member function that copies state from one object into an already existing object of a compatible type.
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