README
¶
Flago
Super simple package for binding command-line flags to your struct.
Installation
go get github.com/KimMachineGun/flago
Example
package main
import (
"fmt"
"log"
"strings"
"time"
"github.com/KimMachineGun/flago"
)
type Flags struct {
A string `flago:"a,usage of a"`
B int `flago:"b,usage of b"`
C CommaSeparatedStrings `flago:"c,usage of c"`
D time.Time `flago:"d,usage of d"`
E NestedFlags `flago:"e.,nested flags: "`
}
type NestedFlags struct {
A string `flago:"a,usage of a"`
B int `flago:"b,usage of b"`
}
// CommaSeparatedStrings implements flag.Value.
type CommaSeparatedStrings []string
func (s *CommaSeparatedStrings) String() string {
return strings.Join(*s, ",")
}
func (s *CommaSeparatedStrings) Set(v string) error {
*s = strings.Split(v, ",")
return nil
}
// go run main.go -b=360 -c=Hello,World -d=2020-01-02T00:00:00Z -e.a=CD
func main() {
// set default values
flags := Flags{
A: "AB",
B: 180,
C: []string{"Foo", "Bar"},
D: time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC),
E: NestedFlags{
A: "AB",
B: 180,
},
}
// go run main.go --help
// Output:
// -a string
// usage of a (default "AB")
// -b int
// usage of b (default 180)
// -c value
// usage of c (default Foo,Bar)
// -d value
// usage of d (default 2020-01-01T00:00:00Z)
// -e.a string
// nested flags: usage of a (default "AB")
// -e.b int
// nested flags: usage of b (default 180)
// parse flags
err := flago.Parse(&flags)
if err != nil {
log.Fatalln(err)
}
fmt.Println(flags)
// Output: {AB 360 [Hello World] 2020-01-02 00:00:00 +0000 UTC {CD 180}}
}
Documentation
¶
Index ¶
- func Bind(fs *flag.FlagSet, v interface{}) error
- func BindEnvExpanded(fs *flag.FlagSet, v interface{}) error
- func BindEnvExpandedWithPrefix(fs *flag.FlagSet, v interface{}, prefix string) error
- func BindWithPrefix(fs *flag.FlagSet, v interface{}, prefix string) error
- func Parse(v interface{}) error
- func ParseEnvExpanded(v interface{}) error
- func ParseEnvExpandedWithPrefix(v interface{}, prefix string) error
- func ParseWithPrefix(v interface{}, prefix string) error
- type InvalidBindError
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Bind ¶
Bind defines flags based on the struct field tags and binds flags to the corresponding fields. If v is nil or not a pointer of struct, Bind returns InvalidBindError.
Bind uses 'flago' field tag to specify the name and usage of the flag. If a field does not have a 'flago' field tag, it will be ignored.
If a field is struct type, Bind will parse it recursively, and its field tag will be used as a prefix of the names of the flags defined by itself.
Supported Field Types:
- string
- bool
- int
- int64
- uint
- uint64
- float64
- time.Duration
- flag.Value
Examples:
type Example struct {
// Name defines a 'name' flag, and its usage message is not set (empty string).
Name string `flago:"name"`
// Age defines a 'age' flag, and its usage message is 'the age of gopher'.
// The name and usage specified in the field tag are separated by comma.
// flag.IntVar()
Age int `flago:"age,the age of gopher"`
// Nested defines a 'nested.*' flag, and its usage prefix is 'nested flags: '.
// Nested is a struct type, so Bind will parse it recursively.
Nested struct {
// NestedName defines a 'name' flag, and its usage message is 'nested name'.
// Since NestedName is a field of Nested, the name of the flag will be 'nested.name',
// and its usage message will be 'nested flags: nested name'.
NestedName string `flago:"name,nested name"`
} `flago:"nested,nested flags: "`
}
func BindEnvExpanded ¶ added in v0.4.0
BindEnvExpanded defines env-expanded flags based on the struct field tags and binds flags to the corresponding fields.
func BindEnvExpandedWithPrefix ¶ added in v0.4.0
BindEnvExpandedWithPrefix defines env-expanded flags with prefix.
func BindWithPrefix ¶ added in v0.3.0
BindWithPrefix defines flags with prefix. See the comments of Bind for more details.
func Parse ¶ added in v0.5.0
func Parse(v interface{}) error
Parse parses the default command-line flag set defined in the flag package.
func ParseEnvExpanded ¶ added in v0.6.0
func ParseEnvExpanded(v interface{}) error
ParseEnvExpanded parses the default command-line flag set defined in the flag package. Unlike Parse, it expands environment variables in the flag values.
func ParseEnvExpandedWithPrefix ¶ added in v0.6.0
ParseEnvExpandedWithPrefix parses the default command-line flag set defined in the flag package with prefix. Unlike ParseWithPrefix, it expands environment variables in the flag values.
func ParseWithPrefix ¶ added in v0.6.0
ParseWithPrefix parses the default command-line flag set defined in the flag package with prefix.
Types ¶
type InvalidBindError ¶
An InvalidBindError describes an invalid argument passed to Bind.
func (*InvalidBindError) Error ¶
func (e *InvalidBindError) Error() string
Source Files