CODEWITHSUNDEEP
flutterdart
Kavin Raju S
Kavin Raju S

Reputation: 1382

What is .. operator in dart?

Widget customWidget(int position){
    return Transform(
    transform: Matrix4.identity()..rotateY(position),
    child: Container(
      color: position % 2 == 0 ? Colors.lightBlueAccent: Colors.black87,
    ),
  )
}

What is .. in Matrix4.identity()..rotateY(position) ?

Upvotes: 1

Views: 798

Answers (2)

Praneeth Dhanushka Fernando
Praneeth Dhanushka Fernando

Reputation: 3263

Cascade notation

From the official documentation

Cascades (..) allow you to make a sequence of operations on the same object.

In addition to function calls, you can also access fields on that same object. This often saves you the step of creating a temporary variable and allows you to write more fluid code.

Upvotes: 3

TheMri
TheMri

Reputation: 1297

From the official docs ,

Cascades (..) allow you to make a sequence of operations on the same object. In addition to function calls, you can also access fields on that same object. This often saves you the step of creating a temporary variable and allows you to write more fluid code.

Consider the following code:

querySelector('#confirm') // Get an object.
  ..text = 'Confirm' // Use its members.
  ..classes.add('important')
  ..onClick.listen((e) => window.alert('Confirmed!'));

The first method call, querySelector(), returns a selector object. The code that follows the cascade notation operates on this selector object, ignoring any subsequent values that might be returned.

The previous example is equivalent to:

var button = querySelector('#confirm');
button.text = 'Confirm';
button.classes.add('important');
button.onClick.listen((e) => window.alert('Confirmed!'))

Upvotes: 1

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