CODEWITHSUNDEEP
flutterstream
Bishara Azar
Bishara Azar

Reputation: 31

the meaning of the ( get ) keyword with Streams in flutter

Sink<List<FoodItem>> get listSink => _listController.sink;

Can someone explain to me what does the (get) do ?

this is the default sink function

Upvotes: 2

Views: 1873

Answers (3)

Andrija
Andrija

Reputation: 1909

To add to @Maxouille's answer:

If you make a property public in Java, and then decide to make it private (because you had to add some additional logic in your get/set methods), calling syntax would change - e.g. instead of A.nValue++; you would have A.setNValue(A.getNValue()++);. This is why convention in Java is to make all properties private from the beginning, and wrap them with get/set methods. This ends up with bunch of code that does nothing, but is there 'just in case'.

What this nice syntax enables you is to convert your public properties easily to private properties with get/set wrapper methods - without changing calling code.

In the above example - property nValue could have started as a simple int property. Once you decide to make it private - you change your class like in the example above: create a new private variable _n and convert your nValue into get/set properties:

int get nValue => _n;
set nValue(int newValue) => _n=newValue;

Your calling code would still remain the same nValue++;

Upvotes: 1

Maxouille
Maxouille

Reputation: 2911

This is the syntax of getter methods in dart.

You have a private parameter defined by the _. Every variable that starts with an underscore is considered as private and can't be read outside of the class. From the documentation :

Unlike Java, Dart doesn’t have the keywords public, protected, and private. If an identifier starts with an underscore _, it’s private to its library.

The getter syntax is something like :

Return type get myVarName => the private value you want to return

Imagine this very simple class:

class A {
   int _n = 42;
   
   int get nValue => _n;
}

In order to access the value of n from class A, I need to use a getter as n is private.

A myClass = A();

A.n; // Error as n is private

A.nValue; // Return 42.

Upvotes: 4

VLXU
VLXU

Reputation: 729

The keyword get indicates a getter in dart.

To be more specific, a getter is part of the class interface that allows you to retrieve a certain value from a class instance. In Dart, you can think of it almost like a method that doesn't take parameters and uses syntax that is similar to accessing a field value (i.e., attribute) from a class instance.

For example,

void main() {
  Item myItem = Item(initialCost: 1000);
      
  print(myItem.cost); // 2002
  
  myItem.cost = 100; // Error because there is no setter 'cost' 
}

class Item{

  int _privateCost;
  int initialCost;
  
  int get cost {
     return _privateCost * 2;
  };

  // constructor
  Item({this.initialCost}){
    _privateCost = initialCost + 1;
  }
 
}

Upvotes: 0

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