falcon

Rules / Style / unnecessary-constructor-name

unnecessary-constructor-name

lint/style/unnecessary-constructor-name
recommended
Same as unnecessary_constructor_name · Dart lints

Flags a redundant .new on constructor invocations.

X.new(...) names the default (unnamed) constructor explicitly, which is exactly equivalent to the shorter X(...), so the .new is noise. The rule catches both the plain call form (X.new(...)) and the new/const form (const X.new(...)). A bare X.new constructor tear-off that is not invoked is deliberately left alone: there the .new is required to reference the constructor as a value.

Invalid

example.dartdart
// Bad: explicit `.new` on a constructor invocation is redundant.
class Foo {
  Foo();
}

void examples() {
  final a = Foo.new();
  final b = Foo.new()..toString();
  final c = <Foo>[Foo.new()];
  final d = identical(a, Foo.new());
  final e = Foo.new();
  final g = Foo.new();
  print([a, b, c, d, e, g]);
}
Unnecessary `.new`; the default constructor can be invoked without it.
6void examples() {
7 final a = Foo.new();
Unnecessary `.new`; the default constructor can be invoked without it.
7 final a = Foo.new();
8 final b = Foo.new()..toString();
Unnecessary `.new`; the default constructor can be invoked without it.
8 final b = Foo.new()..toString();
9 final c = <Foo>[Foo.new()];
Unnecessary `.new`; the default constructor can be invoked without it.
9 final c = <Foo>[Foo.new()];
10 final d = identical(a, Foo.new());
Unnecessary `.new`; the default constructor can be invoked without it.
10 final d = identical(a, Foo.new());
11 final e = Foo.new();
Unnecessary `.new`; the default constructor can be invoked without it.
11 final e = Foo.new();
12 final g = Foo.new();

Valid

example.dartdart
// Good: no redundant `.new`. Bare `X.new` tear-offs keep `.new` (it is required there).
class Foo {
  Foo();
  Foo.named();
}

void examples() {
  final tearOff = Foo.new; // tear-off of the default constructor — `.new` required
  final a = Foo();
  final b = Foo.named();
  final list = [1, 2, 3].map((_) => Foo.new).toList();
  final c = Foo.named()..toString();
  final d = StringBuffer();
  print([tearOff, a, b, list, c, d]);
}

How to configure

Set the severity of unnecessary-constructor-name in your falcon.json:

falcon.jsonjson
{
  "linter": {
    "rules": {
      "style": {
        "unnecessary-constructor-name": "error"
      }
    }
  }
}

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