apishape

What it detects

Reports exported functions with too many parameters, long runs of parameters that share one type, and adjacent optional scalar parameters that are easy to swap. It also reports types that mix pointer and value receiver methods.

Checks

Check	What it detects
parameter-count*	Reports exported APIs with more than the configured maximum number of parameters.
mixed-receivers*	Reports types that mix pointer and value receiver methods.
adjacent-same-type*	Reports long adjacent runs of parameters that share one type.
adjacent-optional-scalars*	Reports adjacent optional scalar parameters that are easy to swap.

* Opt-in; requires explicit selection.

Why this is flagged

Long parameter lists are difficult to read at call sites, and adjacent values of the same type can be swapped without the compiler noticing. Grouping related values in a named type makes each argument’s meaning explicit and makes the API safer to change later.

How to fix it

Put related parameters into a small, clearly named options or request type. When two adjacent values could be confused, give them distinct named types or group them into a type whose field names explain their purpose.

Examples

Flagged code

Too many parameters

// gohawk: exported API has 5 parameters; use an Input or config struct
func CreateUser(name string, age int, active bool, score float64, role byte) error {
  return nil
}

Adjacent optional parameters

// gohawk: adjacent optional scalar parameters are easy to swap; use an Input struct
func FindUser(firstName, lastName *string) error {
  return nil
}

Accepted code

type CreateUserInput struct {
  Name, Email, City, Country, Role string
}

func CreateUserWithInput(input CreateUserInput) error {
  return nil
}

Options

Knob	Default	Effect
max-adjacent-same-type	2	Maximum adjacent parameters of one type; 0 disables the check.
max-parameters	4	Maximum exported function parameters; 0 disables the check.