dart spread operator with nested map

mathiasgodwin answered on August 23, 2022 Popularity 1/10 Helpfulness 1/10

answer dart spread operator with nested map

dart spread operator with nested map

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import 'dart:convert';

main(){
  // Define sourceA
      var sourceA = {
        "nested": {
          "value": 10
        }
      };

      // Define sourceB
      var sourceB = {
        "sourceA": {...sourceA}
      };
  

      // Clone both sources into two new maps
      var m1 = {...sourceA};
      var m2 = {...sourceB};
      var m3 = json.decode(json.encode(sourceB)); // deep copy

      print(m2["sourceA"]!["nested"] == m1["nested"]); // prints true
      print(m3["sourceA"]!["nested"] == m1["nested"]); // prints false

      // Check hash codes
      print(m2["sourceA"]!["nested"].hashCode); // prints 418854379
      print(m3["sourceA"]!["nested"].hashCode); // prints 892131505
      print(m1["nested"].hashCode);             // prints 418854379

      // Change the nested value of m3
      // m2["sourceA"]!["nested"]!["value"] = 11;
      m3["sourceA"]!["nested"]!["value"] = 11;

      // Observe it has been changed in m1
      print(m1["nested"]!["value"]); // prints 10
}

Popularity 1/10 Helpfulness 1/10 Language dart

Source: stackoverflow.com

Tags: dart nested-map spread

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Contributed on Aug 23 2022

mathiasgodwin

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dart spread operator with nested map

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