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[Flutter/dart] Private and final class variable


Overview


Suppose adding a class variable in dart like below.

  • Private (don't want to be accessed from outside)

  • Determine the value by referring to the arguments of the constructor

  • Once the value is set above, it will not change after that

In such a case, this variable should be final.

I will introduce this method.



Method


The first thing that comes to mind is, why not just set the value inside the constructor.

A final variable cannot be set inside the constructor.

class AClass{
  
  final String _title;
  ・・・
  
  Genre({required String name}){
    _title = setTitle(name);   //compile error
  }
}

Set value in an initializer.

class AClass{
  
  final String _title;
  ・・・
  
  Genre({required String name}):
    _title = setTitle(name);   
}


Lastly


It's easy once you know how, but it took me a while to figure it out, because

I haven't used final much so far...

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