flagx

func BoolFunc ¶ added in v0.22.2

func BoolFunc(fs *flag.FlagSet, name, usage string, fn func() error)

BoolFunc defines a flag with the specified name and usage string. Each time the flag is set with a truthy value, fn is called. If fn returns a non-nil error, it will be treated as a flag value parsing error.

Output:

called!

func Missing ¶

func Missing(err error) []string

Missing returns a slice of required flags missing from an error returned by MustHave.

func MustHave ¶

func MustHave(fl *flag.FlagSet, names ...string) error

MustHave is a convenience function that checks that the named flags were set on fl. Missing flags are treated with the policy of fl.ErrorHandling(): ExitOnError, ContinueOnError, or PanicOnError. Returned errors can be unpacked by Missing.

If nil, fl defaults to flag.CommandLine.

Output:

missing required flag: b
Usage of ExampleMustHave:
  -a string
    	this value must be set
  -b string
    	this value must be set
  -c string
    	this value is optional
Missing: [b]

Output:

func MustHaveArgs ¶

func MustHaveArgs(fl *flag.FlagSet, min, max int) error

MustHaveArgs is a convenience function that checks that fl.NArg() is within the bounds min and max (inclusive). Use max -1 to indicate no maximum value. MustHaveArgs uses the policy of fl.ErrorHandling(): ExitOnError, ContinueOnError, or PanicOnError.

If nil, fl defaults to flag.CommandLine.

Output:

Output:

must have between 0 and 1 args; got 2
Usage:
	ExampleMustHaveArgs [optional arg]

func ParseEnv ¶

func ParseEnv(fl *flag.FlagSet, prefix string) error

ParseEnv lists any unset flags, checks whether a corresponding environment variable exists, and if so calls Set with its value. Flag names are prefixed and converted to SCREAMING_SNAKE_CASE when looking up environment variables.

Output:

a 1
b 3