avoid_long_files

v1.0.0WarningConfigurableCode Quality

This rule flags a file longer than the configured line budget.

Why use this rule

A long file is where a module stops having a single subject: the name at the top no longer describes everything below it, and finding the right place to add something becomes a scroll rather than a decision.

Blank lines and comments are not counted by default — a file is not hard to navigate because it is well documented. Lines are counted from the token stream, so a // inside a string literal is never mistaken for a comment.

Generated files are the obvious exception, and per-rule exclude handles them:

rules:
  avoid_long_files:
    exclude: ["**/*.g.dart", "**/*.freezed.dart"]

This rule is in the pedantic preset: a budget is a house style, and the right number differs per codebase.

Don’t

// user_page.dart — 800 lines holding the page, its three dialogs,
// a formatter, and the API client it calls.

Do

// user_page.dart          — the page
// user_page_dialogs.dart   — its dialogs
// user_formatting.dart     — the formatter
// user_api.dart            — the client

Enabling this rule

This rule is in the pedantic preset, so it is enabled by preset: pedantic or by name:

rules:
  avoid_long_files:
    enabled: true

many_lints:
  rules:
    avoid_long_files:
      max_lines: 300
      count_comments: false

rules:
  avoid_long_files:
    max_lines: 300
    count_comments: false

Option	Type	Default	Description
`max_lines`	int	`300`	How many code lines a file may hold
`count_comments`	bool	`false`	Whether blank lines and comments count toward the budget

Turning this rule off

To disable this rule:

rules:
  avoid_long_files: false

To keep the rule on but skip certain paths, use per-rule exclude.

avoid_long_parameter_list — Keep parameter lists within a budget.
avoid_too_many_methods — Keep a class within a method budget.
max_imports — Keep a file within an import budget.
avoid_long_functions — Keep function bodies within a line budget.