Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
It is suggested that you use the Golang module spf13/cobra (instead of the standard Golang library flag) for parsing command-line arguments.
import (
"flag"
"fmt"
)Declare a string flag --name with a default value “Ben” and a short description.
Notice that the function flag.String returns a string pointer (not a string value).
wordPtr := flag.String("name", "Ben", "Name of a person.")numbPtr := flag.Int("numb", 42, "an int")
forkPtr := flag.Bool("fork", false, "a bool")flag.Parse()*wordPtrBen*numbPtr42*forkPtrfalseflag.Args()[/home/dclong/.local/share/jupyter/runtime/kernel-9d64ca68-de95-4d2c-a5a1-256edc785832.json]Sub Commands¶
You can define sub-commands using flag.NewFlagSet.
However,
flag does not automatically generate help docs for sub-commands defined
(which is not as convenient as argparse in Python).
One way to improve the default behavior here
is to overwrite the -h option for the main command
and print help documentation on sub-commands when -h is specified.
Below is such an example.
package main
import "flag"
import "fmt"
import "os"
func main() {
help := flag.Bool("h", false, "show help doc")
fooCmd := flag.NewFlagSet("foo", flag.ExitOnError)
barCmd := flag.NewFlagSet("bar", flag.ExitOnError)
flag.Parse()
if *help {
fmt.Printf(`Usage of %s
foo - help doc on foo
bar - help doc on bar
`, os.Args[0])
os.Exit(0)
}
switch os.Args[1] {
case "foo": _parse_foo(fooCmd)
case "bar": _parse_bar(barCmd)
}
}
func _parse_foo(fooCmd *flag.FlagSet) {
fooEnable := fooCmd.Bool("enable", false, "enable")
fooName := fooCmd.String("name", "", "name")
fooCmd.Parse(os.Args[2:])
fmt.Println("subcommand 'foo'")
fmt.Println(" enable:", *fooEnable)
fmt.Println(" name:", *fooName)
fmt.Println(" tail:", fooCmd.Args())
}
func _parse_bar(barCmd *flag.FlagSet) {
barLevel := barCmd.Int("level", 0, "level")
barCmd.Parse(os.Args[2:])
fmt.Println("subcommand 'bar'")
fmt.Println(" level:", *barLevel)
fmt.Println(" tail:", barCmd.Args())
}