avoid_long_parameter_list

v1.0.0WarningConfigurableCode Quality

This rule flags a function taking more parameters than the configured budget.

Why use this rule

A long parameter list is usually several values that belong together travelling separately, and every caller has to assemble them in the right order. Grouping them into a record or a small class names the thing they form and makes the call sites read.

Positional and named parameters are counted separately, with a larger budget for named. Named parameters are labelled at the call site and do not depend on order, so a widget constructor with eight of them is not the problem this rule exists for — the default budgets are 4 positional and 10 named.

An @override is never reported, since it cannot change its signature.

This rule is in the pedantic preset: a parameter budget is a house style.

Don’t

void schedule(
  String title,
  DateTime start,
  DateTime end,
  String venue,
  int courtNumber,
) {}

Do

void schedule(String title, DateRange when, Court court) {}

Enabling this rule

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

rules:
  avoid_long_parameter_list:
    enabled: true

many_lints:
  rules:
    avoid_long_parameter_list:
      max_positional: 3
      max_named: 12

rules:
  avoid_long_parameter_list:
    max_positional: 3
    max_named: 12

Option	Type	Default	Description
`max_positional`	int	`4`	How many positional parameters are allowed
`max_named`	int	`10`	How many named parameters are allowed

Turning this rule off

To disable this rule:

rules:
  avoid_long_parameter_list: false

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

avoid_long_files — Keep a file within a line 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.