no_wildcard_variable_uses

Don't use wildcard parameters or variables.

DON'T use wildcard parameters or variables.

Wildcard parameters and local variables (e.g. underscore-only names like _, __, ___, etc.) will become non-binding in a future version of the Dart language. Any existing code that uses wildcard parameters or variables will break. In anticipation of this change, and to make adoption easier, this lint disallows wildcard and variable parameter uses.

BAD:

var _ = 1;
print(_); // LINT

void f(int __) {
  print(__); // LINT multiple underscores too
}

GOOD:

for (var _ in [1, 2, 3]) count++;

var [a, _, b, _] = [1, 2, 3, 4];

To enable the no_wildcard_variable_uses rule, add no_wildcard_variable_uses under linter > rules in your analysis_options.yaml file:

linter:
  rules:
    - no_wildcard_variable_uses

If you're instead using the YAML map syntax to configure linter rules, add no_wildcard_variable_uses: true under linter > rules:

linter:
  rules:
    no_wildcard_variable_uses: true

Unless stated otherwise, the documentation on this site reflects Dart 3.6.0. Page last updated on 2025-01-27. View source or report an issue.