pflags

Documentation

Overview

Package pflags provides declarative options and a string-slice option type.

Index

• Constants
• Variables
• func HelpOptions() (optionNames []string)
• func NewStringSliceValue(slicePointer *[]string, defaultValue []string) (v flag.Value)
• func OptionValues(optionData []OptionData) (effectiveValueMap, defaultsMap map[string]string)
• type ArgParser
  • func NewArgParser(optionsList []OptionData, usage func()) (argParser *ArgParser)
  • func (a *ArgParser) Parse()
• type OptionData
  • func (o *OptionData) AddOption()
  • func (o *OptionData) ApplyYaml() (err error)
  • func (o *OptionData) ValueDump() (valueS string)
• type StringSliceValue
  • func (v *StringSliceValue) Set(optionValue string) (err error)
  • func (v StringSliceValue) String() (s string)
• type VisitedOptions
  • func NewVisitedOptions() (o *VisitedOptions)
  • func (o *VisitedOptions) Map() (m map[string]bool)
  • func (o *VisitedOptions) Slice() (s []string)

Constants

const (
	// the os.Args value of debug option: “-debug”
	DebugOption = "-" + DebugOptionName
	// the name of debug option “debug”
	DebugOptionName = "debug"
)

Variables

var NoOptions []OptionData

Functions

func HelpOptions

func HelpOptions() (optionNames []string)

returns implicit help options: "h" "help"

func NewStringSliceValue

func NewStringSliceValue(slicePointer *[]string, defaultValue []string) (v flag.Value)

NewStringSliceValue initializes a slice option

• the option’s value is stored in a slice at slicePointer
• defaultValue may be nil
• flag.Value is an interface of the flag package storing non-standard value types

func OptionValues

func OptionValues(optionData []OptionData) (effectiveValueMap, defaultsMap map[string]string)

OptionValues returns a printable map of current values

• %v: map[debug:false …]

Types

type ArgParser

type ArgParser struct {
	// contains filtered or unexported fields
}

ArgParser invokes flag.Parse with off-flags support. pflags package compared to flags package:

• ability to use declarative options
• ability to read default option values from yaml configuration files
• support for multiple-strings option value
• support for unary off-flags, “-no-flag” options
• map or list of visited options

func NewArgParser

func NewArgParser(optionsList []OptionData, usage func()) (argParser *ArgParser)

NewArgParser returns an options-parser with off-flags support

func (*ArgParser) Parse

func (a *ArgParser) Parse()

Parse invokes flag.Parse after providing optionsList and usage to flag package

• -no-flagname flags are inverted before and after

type OptionData

type OptionData struct {
	P     interface{} // P is a reference to where the effective value of this option is stored
	Name  string      // Name is the option name without hyphen, “debug” for -debug
	Value interface{} // Value is the default value for this option
	Usage string      // printable string describing what this option does
	Y     interface{} // reference to effective value in YamlData
}

OptionData contain options data for the flag package

• OptionData is used for command-line options to be declarative
• instead of flag.BoolVar and similar invocations scattered about the codebase all options are in a single OptionData slice that is iterated so that AddOption is invoked for each element
• to invoke flag.BoolVar. pointer, name, value and usage is required
• flag.BoolVar is consumer-provided storage, flag.Bool is flag-provided storage

func (*OptionData) AddOption

func (o *OptionData) AddOption()

AddOption executes flag.BoolVar and such on the options map

• this defines the option to the flag package
• all options must be defined prior to invoking flag.Parse
• options are defined using value pointers, ie flag.BoolVar not flag.Bool[], so flag.Parse updates effective option values directly

func (*OptionData) ApplyYaml

func (o *OptionData) ApplyYaml() (err error)

ApplyYaml copies a value read from yaml into the effective value location

func (*OptionData) ValueDump

func (o *OptionData) ValueDump() (valueS string)

type StringSliceValue

type StringSliceValue struct {
	// contains filtered or unexported fields
}

StringSliceValue manages a string-slice value for flag.Var

func (*StringSliceValue) Set

func (v *StringSliceValue) Set(optionValue string) (err error)

Set updates the string slice

• Set is invoked once for each option-occurrence in the command line
• Set appends each such option value to its list of strings

func (StringSliceValue) String

func (v StringSliceValue) String() (s string)

flag package invoke String to render default value

type VisitedOptions

type VisitedOptions struct {
	// contains filtered or unexported fields
}

func NewVisitedOptions

func NewVisitedOptions() (o *VisitedOptions)

func (*VisitedOptions) Map

func (o *VisitedOptions) Map() (m map[string]bool)

func (*VisitedOptions) Slice

func (o *VisitedOptions) Slice() (s []string)