The `const` constructor

[SimonLab]

I recently blocked on a line similar to:

final myList = const [1,2,3];

I wan't sure about the meaning of const when initialising a final variable. In this situation const is used to instanciate (create) a new immutable object. This means that the list object [1, 2, 3] can't be changed, and the following code won't work:

final myList = const [1, 2, 3];
myList.add(4); // error

If we ignore const then we are able to use the function add on the list, and this following code will work:

final myList = [1, 2, 3]
myList.add(4) // myList contains now the value [1, 2, 3, 4]

ref:

• https://dart.dev/guides/language/language-tour#constructors
• https://dart.dev/guides/language/language-tour#using-constructors
• https://stackoverflow.com/questions/21744677/how-does-the-const-constructor-actually-work/21746692#21746692
• https://stackoverflow.com/questions/52581148/when-is-const-optional-in-dart-2