README

interfacer

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A linter that suggests interface types. In other words, it warns about the usage of types that are more specific than necessary.

go get -u github.com/mvdan/interfacer/cmd/interfacer
Usage
func ProcessInput(f *os.File) error {
        b, err := ioutil.ReadAll(f)
        if err != nil {
                return err
        }
        return processBytes(b)
}
$ interfacer $(go list ./... | grep -v /vendor/)
foo.go:10:19: f can be io.Reader
Basic idea

This tool inspects the parameters of your functions to see if they fit an interface type that is less specific than the current type.

The example above illustrates this point. Overly specific interfaces also trigger a warning - if f were an io.ReadCloser, the same message would appear.

It suggests interface types defined both in the func's package and the package's imports (two levels; direct imports and their direct imports).

False positives

To avoid false positives, it never does any suggestions on functions that may be implementing an interface method or a named function type.

It also skips parameters passed by value (excluding pointers and interfaces) on unexported functions, since that would introduce extra allocations where they are usually not worth the tradeoff.

Suppressing warnings

If a suggestion is technically correct but doesn't make sense, you can still suppress the warning by mentioning the type in the function name:

func ProcessInputFile(f *os.File) error {
	// use as an io.Reader
}
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Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func CheckArgs

func CheckArgs(args []string) ([]string, error)

CheckArgs checks the packages specified by their import paths in args.

func Interfacer

func Interfacer(packagesPath map[string]string) []string

Types

type Checker

type Checker struct {
	*loader.PackageInfo

	// contains filtered or unexported fields

}

func (*Checker) Check

func (c *Checker) Check() ([]lint.Issue, error)

func (*Checker) Program

func (c *Checker) Program(lprog *loader.Program)

func (*Checker) ProgramSSA

func (c *Checker) ProgramSSA(prog *ssa.Program)

func (*Checker) Visit

func (c *Checker) Visit(node ast.Node) ast.Visitor

type Issue

type Issue struct {

	// contains filtered or unexported fields

}

func (Issue) Message

func (i Issue) Message() string

func (Issue) Pos

func (i Issue) Pos() token.Pos