Cascade Operator | Chinese Rule of Eight

Give a ClosedPath class like so:

import 'dart:math';

class ClosedPath {

List <Point> _points = [];

// we create new array starting on new point

void moveTo(Point point) {

_points = [point];

}

// add a point to our array so we can make a line from the previous index point to this point.

void lineTo(Point point) {

_points.add(point);

}

In the main, we call its functions to draw a shape, you’ll do something like so:

import 'path.dart';

import 'dart:math';

void main() {

final path = ClosedPath();

path.moveTo(Point(0,0));

path.lineTo(Point(2,0));

path.lineTo(Point(2,2));

path.lineTo(Point(0,2));

path.lineTo(Point(0,0));

}

However, using the cascade operator, we can simply it to this:

ClosedPath()

..moveTo(Point(0,0))

..lineTo(Point(2,0))

..lineTo(Point(2,2))

..lineTo(Point(0,2))

..lineTo(Point(0,0));

Notice there is no semi-colon in the end. Instead, we use .. operator to depict calling another function on the same instance.