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flag2.go
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flag2.go
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package flag2
import (
"fmt"
"os"
"time"
)
// CommandLine is the default FlagSet used by the package-level functions
var CommandLine = NewFlagSet(os.Args[0], ExitOnError)
// VisitAll visits the command-line flags in lexicographical order, calling
// fn for each. It visits all flags, even those not set.
func VisitAll(fn func(*Flag)) {
CommandLine.VisitAll(fn)
}
// Visit visits the command-line flags in lexicographical order, calling fn
// for each. It visits only those flags that have been set.
func Visit(fn func(*Flag)) {
CommandLine.Visit(fn)
}
// Lookup returns the Flag structure of the named command-line flag,
// returning nil if none exists.
func Lookup(name string) *Flag {
return CommandLine.formal[name]
}
// Set sets the value of the named command-line flag.
func Set(name, value string) error {
return CommandLine.Set(name, value)
}
// PrintDefaults prints, to standard error unless configured otherwise,
// a usage message showing the default settings of all defined
// command-line flags.
// For an integer valued flag x, the default output has the form
// -x int
// usage-message-for-x (default 7)
// The usage message will appear on a separate line for anything but
// a bool flag with a one-byte name. For bool flags, the type is
// omitted and if the flag name is one byte the usage message appears
// on the same line. The parenthetical default is omitted if the
// default is the zero value for the type. The listed type, here int,
// can be changed by placing a back-quoted name in the flag's usage
// string; the first such item in the message is taken to be a parameter
// name to show in the message and the back quotes are stripped from
// the message when displayed. For instance, given
// flag.String("I", "", "search `directory` for include files")
// the output will be
// -I directory
// search directory for include files.
func PrintDefaults() {
CommandLine.PrintDefaults()
}
// NOTE: Usage is not just defaultUsage(CommandLine)
// because it serves (via godoc flag Usage) as the example
// for how to write your own usage function.
// Usage prints a usage message documenting all defined command-line flags
// to CommandLine's output, which by default is os.Stderr.
// It is called when an error occurs while parsing flags.
// The function is a variable that may be changed to point to a custom function.
// By default it prints a simple header and calls PrintDefaults; for details about the
// format of the output and how to control it, see the documentation for PrintDefaults.
// Custom usage functions may choose to exit the program; by default exiting
// happens anyway as the command line's error handling strategy is set to
// ExitOnError.
var Usage = func() {
fmt.Fprintf(CommandLine.Output(), "Usage of %s:\n", os.Args[0])
PrintDefaults()
}
// NFlag returns the number of command-line flags that have been set.
func NFlag() int { return len(CommandLine.actual) }
// Arg returns the i'th command-line argument. Arg(0) is the first remaining argument
// after flags have been processed. Arg returns an empty string if the
// requested element does not exist.
func Arg(i int) string {
return CommandLine.Arg(i)
}
// NArg is the number of arguments remaining after flags have been processed.
func NArg() int { return len(CommandLine.args) }
// Args returns the non-flag command-line arguments.
func Args() []string { return CommandLine.args }
// BoolVar defines a bool flag with specified name, default value, and usage string.
// The argument p points to a bool variable in which to store the value of the flag.
func BoolVar(p *bool, name string, value bool, usage string, options ...FlagOption) {
CommandLine.Var(newBoolValue(value, p), name, usage, options...)
}
// Bool defines a bool flag with specified name, default value, and usage string.
// The return value is the address of a bool variable that stores the value of the flag.
func Bool(name string, value bool, usage string, options ...FlagOption) *bool {
return CommandLine.Bool(name, value, usage, options...)
}
// IntVar defines an int flag with specified name, default value, and usage string.
// The argument p points to an int variable in which to store the value of the flag.
func IntVar(p *int, name string, value int, usage string, options ...FlagOption) {
CommandLine.Var(newIntValue(value, p), name, usage, options...)
}
// Int defines an int flag with specified name, default value, and usage string.
// The return value is the address of an int variable that stores the value of the flag.
func Int(name string, value int, usage string, options ...FlagOption) *int {
return CommandLine.Int(name, value, usage, options...)
}
// Int64Var defines an int64 flag with specified name, default value, and usage string.
// The argument p points to an int64 variable in which to store the value of the flag.
func Int64Var(p *int64, name string, value int64, usage string, options ...FlagOption) {
CommandLine.Var(newInt64Value(value, p), name, usage, options...)
}
// Int64 defines an int64 flag with specified name, default value, and usage string.
// The return value is the address of an int64 variable that stores the value of the flag.
func Int64(name string, value int64, usage string, options ...FlagOption) *int64 {
return CommandLine.Int64(name, value, usage, options...)
}
// UintVar defines a uint flag with specified name, default value, and usage string.
// The argument p points to a uint variable in which to store the value of the flag.
func UintVar(p *uint, name string, value uint, usage string, options ...FlagOption) {
CommandLine.Var(newUintValue(value, p), name, usage, options...)
}
// Uint defines a uint flag with specified name, default value, and usage string.
// The return value is the address of a uint variable that stores the value of the flag.
func Uint(name string, value uint, usage string, options ...FlagOption) *uint {
return CommandLine.Uint(name, value, usage, options...)
}
// Uint64Var defines a uint64 flag with specified name, default value, and usage string.
// The argument p points to a uint64 variable in which to store the value of the flag.
func Uint64Var(p *uint64, name string, value uint64, usage string, options ...FlagOption) {
CommandLine.Var(newUint64Value(value, p), name, usage, options...)
}
// Uint64 defines a uint64 flag with specified name, default value, and usage string.
// The return value is the address of a uint64 variable that stores the value of the flag.
func Uint64(name string, value uint64, usage string, options ...FlagOption) *uint64 {
return CommandLine.Uint64(name, value, usage, options...)
}
// StringVar defines a string flag with specified name, default value, and usage string.
// The argument p points to a string variable in which to store the value of the flag.
func StringVar(p *string, name string, value string, usage string, options ...FlagOption) {
CommandLine.Var(newStringValue(value, p), name, usage, options...)
}
// String defines a string flag with specified name, default value, and usage string.
// The return value is the address of a string variable that stores the value of the flag.
func String(name string, value string, usage string, options ...FlagOption) *string {
return CommandLine.String(name, value, usage, options...)
}
// Float64Var defines a float64 flag with specified name, default value, and usage string.
// The argument p points to a float64 variable in which to store the value of the flag.
func Float64Var(p *float64, name string, value float64, usage string, options ...FlagOption) {
CommandLine.Var(newFloat64Value(value, p), name, usage, options...)
}
// Float64 defines a float64 flag with specified name, default value, and usage string.
// The return value is the address of a float64 variable that stores the value of the flag.
func Float64(name string, value float64, usage string, options ...FlagOption) *float64 {
return CommandLine.Float64(name, value, usage, options...)
}
// DurationVar defines a time.Duration flag with specified name, default value, and usage string.
// The argument p points to a time.Duration variable in which to store the value of the flag.
// The flag accepts a value acceptable to time.ParseDuration.
func DurationVar(p *time.Duration, name string, value time.Duration, usage string, options ...FlagOption) {
CommandLine.Var(newDurationValue(value, p), name, usage, options...)
}
// Duration defines a time.Duration flag with specified name, default value, and usage string.
// The return value is the address of a time.Duration variable that stores the value of the flag.
// The flag accepts a value acceptable to time.ParseDuration.
func Duration(name string, value time.Duration, usage string, options ...FlagOption) *time.Duration {
return CommandLine.Duration(name, value, usage, options...)
}
// Var defines a flag with the specified name and usage string. The type and
// value of the flag are represented by the first argument, of type Value, which
// typically holds a user-defined implementation of Value. For instance, the
// caller could create a flag that turns a comma-separated string into a slice
// of strings by giving the slice the methods of Value; in particular, Set would
// decompose the comma-separated string into the slice.
func Var(value Value, name string, usage string, options ...FlagOption) {
CommandLine.Var(value, name, usage, options...)
}
// Parse parses the command-line flags from os.Args[1:]. Must be called
// after all flags are defined and before flags are accessed by the program.
func Parse(options ...ParseOption) {
// Ignore errors; CommandLine is set for ExitOnError.
CommandLine.Parse(os.Args[1:], options...)
}
// Parsed reports whether the command-line flags have been parsed.
func Parsed() bool {
return CommandLine.Parsed()
}
func init() {
// Override generic FlagSet default Usage with call to global Usage.
// Note: This is not CommandLine.Usage = Usage,
// because we want any eventual call to use any updated value of Usage,
// not the value it has when this line is run.
CommandLine.Usage = commandLineUsage
}
func commandLineUsage() {
Usage()
}