super_goes_last.md

Pattern: Wrong super order in constructor initialization list

Issue: -

Description

DO place the super call last in a constructor initialization list.

Field initializers are evaluated in the order that they appear in the constructor initialization list. If you place a super() call in the middle of an initializer list, the superclass's initializers will be evaluated right then before evaluating the rest of the subclass's initializers.

What it doesn't mean is that the superclass's constructor body will be executed then. That always happens after all initializers are run regardless of where super appears. It's vanishingly rare that the order of initializers matters, so the placement of super in the list almost never matters either.

Getting in the habit of placing it last improves consistency, visually reinforces when the superclass's constructor body is run, and may help performance.

Example of correct code:

View(Style style, List children)
  : _children = children,
   super(style) {

Example of incorrect code:

View(Style style, List children)
  : super(style),
   _children = children {

DEPRECATED: In Dart 2, it is a compile-time error if a superinitializer appears in an initializer list at any other position than at the end so this rule is made redundant by the Dart analyzer's basic checks and is no longer necessary.

The rule will be removed in a future Linter release.

Further Reading

• Linter for Dart - super_goes_last