recursive deep copy for nested collections

pub package

This plugin helps with recursive deep copy for nested collections, such as List, Map, Set, ensuring that the cloned object is independent and does not share references with the original object, so that the cloned and existing object do not affect each other.


Add the following dependency to your pubspec.yaml file:

    deepcopy: ^1.1.2


  • Deep copying of lists, maps, and sets with nested structures.
  • Easy to use by using extensions.
  • Measuring the benchmarks (vs. JSON, vs. FIC)


// import this
import 'package:deepcopy/deepcopy.dart';

// clone it!
List clonedList = originalList.deepcopy();
Map clonedMap = originalMap.deepcopy();
Set clonedSet = originalSet.deepcopy();

that's it!

If you're interested in learning more, check out the example usage

Internal Implementation

The internal implementation is simple. I used the intuitive method of adding items one by one to a new MutableList.

You can check it out here : implementation

  • vs Json Decode/Encode ?

    We may also implement deepcopy using jsonEncode/jsonDecode. However, there were performance benefits to just adding them to the MutableList one by one.

  • why not use fast_immutable_collections (FIC) ?

    When I first thought about creating this plugin, the first thing I thought of was FIC. But unlike IList<int>, the benchmarks for IList<dynamic> were actually even worse.

You can check the benchmark result out here : benchmark

You can also run your own benchmark code if you want.

cd test/benchmark
dart benchmark.dart


  • x add benchmarks for list
  • add benchmarks for set
  • add benchmarks for map

The story behind naming this plugin

At first I thought of names like "deepcopy" or "clone". I chose the shorter of the two, "clone". It didn't show up when I searched it in After implementing all the code, creating a logo, and writing the README, I got an unauthorized error trying to deploy version 1.0. It wasn't until I typed "" into the address bar that I realized that the name had been taken six years earlier. I didn't realize that I might not be able to find the plugin on pub. I thought of "deepcopy" as the next best thing.


If you have a better way, feel free to pull request it!