Packages to Ensure Good Code Style with lint in Flutter

If you are new to Dart and Flutter, you must read Effective Dart: Style to write good code with good style.

During the development process, there might be many times that we forget to write code with good style. That’s why we need the IDE to detect those malformatted and inform us to fix them.

There are 2 packages that can enforce those styles as rules.

pedantic 

This package enforces Dart analyzer settings and best practices which are made and used internally at Google.

After installing the package, you can add this line to start lints.

include: package:pedantic/analysis_options.yaml

Available lints

linter:
  rules:
    - always_declare_return_types
    - always_require_non_null_named_parameters
    - annotate_overrides
    - avoid_empty_else
    - avoid_init_to_null
    - avoid_null_checks_in_equality_operators
    - avoid_relative_lib_imports
    - avoid_return_types_on_setters
    - avoid_shadowing_type_parameters
    - avoid_types_as_parameter_names
    - camel_case_extensions
    - curly_braces_in_flow_control_structures
    - empty_catches
    - empty_constructor_bodies
    - library_names
    - library_prefixes
    - no_duplicate_case_values
    - null_closures
    - omit_local_variable_types
    - prefer_adjacent_string_concatenation
    - prefer_collection_literals
    - prefer_conditional_assignment
    - prefer_contains
    - prefer_equal_for_default_values
    - prefer_final_fields
    - prefer_for_elements_to_map_fromIterable
    - prefer_generic_function_type_aliases
    - prefer_if_null_operators
    - prefer_is_empty
    - prefer_is_not_empty
    - prefer_iterable_whereType
    - prefer_single_quotes
    - prefer_spread_collections
    - recursive_getters
    - slash_for_doc_comments
    - type_init_formals
    - unawaited_futures
    - unnecessary_const
    - unnecessary_new
    - unnecessary_null_in_if_null_operators
    - unnecessary_this
    - unrelated_type_equality_checks
    - use_function_type_syntax_for_parameters
    - use_rethrow_when_possible
    - valid_regexps

lint

This package is a community-driven collection of lint rules for Dart and Flutter codes. It also follows Google’s Effective Dart: Style but is stricter than the pedantic package.

Examples of lint’s configurations:

include: package:lint/analysis_options.yaml

linter:
  rules:
    # ------ Disable individual rules ----- #
    #                 ---                   #
    # Turn off what you don't like.         #
    # ------------------------------------- #

    # Use parameter order as in json response
    always_put_required_named_parameters_first: false
    
    # Util classes are awesome!
    avoid_classes_with_only_static_members: false


    # ------ Enable individual rules ------ #
    #                 ---                   #
    # These rules here are good but too     #
    # opinionated to enable them by default #
    # ------------------------------------- #

    # Make constructors the first thing in every class
    sort_constructors_first: true

    # The new tabs vs. spaces. Choose wisely
    prefer_single_quotes: true
    prefer_double_quotes: true

    # Good packages document everything
    public_member_api_docs: true
    
    # Blindly follow the Flutter code style, which prefers types everywhere
    always_specify_types: true
  
    # Back to the 80s
    lines_longer_than_80_chars: true