varnamelen

A Go Analyzer that checks that the length of a variable's name matches its usage scope:

Variables with short names can be hard to use if the variable is used over a longer span of lines of code. A longer variable name may be easier to comprehend.

The analyzer also checks constants, parameters, named return values, method receivers, and type parameters.

Arbitrary declarations such as f *foo can be ignored, as well as idiomatic ok variables. Conventional Go parameters such as ctx context.Context or t *testing.T will always be ignored.

Example output

test.go:4:2: variable name 'x' is too short for the scope of its usage (varnamelen)
        x := 123
        ^
test.go:6:2: variable name 'i' is too short for the scope of its usage (varnamelen)
        i := 10
        ^

golangci-lint Integration

varnamelen is integrated into golangci-lint (though it may not always be the most recent version.)

Example configuration for golangci-lint:

linters-settings:
  varnamelen:
    # The longest distance, in source lines, that is being considered a "small scope." (defaults to 5)
    # Variables used in at most this many lines will be ignored.
    max-distance: 5
    # The minimum length of a variable's name that is considered "long." (defaults to 3)
    # Variable names that are at least this long will be ignored.
    min-name-length: 3
    # Check method receivers. (defaults to false)
    check-receiver: false
    # Check named return values. (defaults to false)
    check-return: false
    # Check type parameters. (defaults to false)
    check-type-param: false
    # Ignore "ok" variables that hold the bool return value of a type assertion. (defaults to false)
    ignore-type-assert-ok: false
    # Ignore "ok" variables that hold the bool return value of a map index. (defaults to false)
    ignore-map-index-ok: false
    # Ignore "ok" variables that hold the bool return value of a channel receive. (defaults to false)
    ignore-chan-recv-ok: false
    # Optional list of variable names that should be ignored completely. (defaults to empty list)
    ignore-names:
      - err
    # Optional list of variable declarations that should be ignored completely. (defaults to empty list)
    # Entries must be in one of the following forms (see below for examples):
    # - for variables, parameters, named return values, method receivers, or type parameters:
    #   <name> <type>  (<type> can also be a pointer/slice/map/chan/...)
    # - for constants: const <name>
    ignore-decls:
      - c echo.Context
      - t testing.T
      - f *foo.Bar
      - e error
      - i int
      - const C
      - T any
      - m map[string]int

Standalone Usage

The cmd/ folder provides a standalone command line utility. You can build it like this:

go build -o varnamelen ./cmd/

Usage

varnamelen: checks that the length of a variable's name matches its scope

Usage: varnamelen [-flag] [package]

A variable with a short name can be hard to use if the variable is used
over a longer span of lines of code. A longer variable name may be easier
to comprehend.

Flags:
  -V    print version and exit
  -all
        no effect (deprecated)
  -c int
        display offending line with this many lines of context (default -1)
  -checkReceiver
        check method receiver names
  -checkReturn
        check named return values
  -checkTypeParam
        check type parameter names
  -cpuprofile string
        write CPU profile to this file
  -debug string
        debug flags, any subset of "fpstv"
  -fix
        apply all suggested fixes
  -flags
        print analyzer flags in JSON
  -ignoreChanRecvOk
        ignore 'ok' variables that hold the bool return value of a channel receive
  -ignoreDecls value
        comma-separated list of ignored variable declarations
  -ignoreMapIndexOk
        ignore 'ok' variables that hold the bool return value of a map index
  -ignoreNames value
        comma-separated list of ignored variable names
  -ignoreTypeAssertOk
        ignore 'ok' variables that hold the bool return value of a type assertion
  -json
        emit JSON output
  -maxDistance int
        maximum number of lines of variable usage scope considered 'short' (default 5)
  -memprofile string
        write memory profile to this file
  -minNameLength int
        minimum length of variable name considered 'long' (default 3)
  -source
        no effect (deprecated)
  -tags string
        no effect (deprecated)
  -trace string
        write trace log to this file
  -v    no effect (deprecated)

License

This package is licensed under the MIT license.