flags - Golang command-line flag parser
- Fully tested, reliable
- Support flag ShortName (Alias)
- Catches any non-defined flags, and any invalid flag values
- Flags are allowed to come before or after the arguments. The followings are all valid inputs:
$ testapp -i 100 -m 500 arg1 arg2 # flags go first
$ testapp arg1 arg2 --i 100 -m 500 # flags go last
$ testapp arg1 -i 100 arg2 -m=500 # flags go in between argumentsThe parsed results for all 3 statements are identical: i=100, Args=[arg1, arg2], m=500
Installation
go get github.com/simonleung8/flags # installs the flags libraryUsage
package main
import (
"github.com/simonleung8/flags"
"os"
)
func main(){
fc := flags.New()
fc.NewStringFlag("password", "p", "flag for password") //name, short_name and usage of the string flag
fc.Parse(os.Args...) //parse the OS arguments
println("Flag 'password' is set: ", fc.IsSet("p"))
println("Flag 'password' value: ", fc.String("p"))
}Running the above code
$ main -password abc
Flag 'password' is set: true
Flag 'password' value: abc
Available Flag Constructor
Flags: String, Int, float64, Bool, String Slice
NewStringFlag(name string, short_name string, usage string)
NewStringFlagWithDefault(name string, short_name string, usage string, value string)
NewIntFlag(name string, short_name string, usage string)
NewIntFlagWithDefault(name string, short_name string, usage string, value int)
NewFloat64Flag(name string, short_name string, usage string)
NewFloat64FlagWithDefault(name string, short_name string, usage string, value float64)
NewStringSliceFlag(name string, short_name string, usage string) //this flag can be supplied more than 1 time
NewStringSliceFlagWithDefault(name string, short_name string, usage string, value []string)
NewBoolFlag(name string, short_name string, usage string)Functions for flags/args reading
IsSet(flag_name string)bool
String(flag_name string)string
Int(flag_name string)int
Float64(flag_name string)float64
Bool(flag_name string)bool
StringSlice(flag_name string)[]string
Args()[]stringParsing flags and arguments
Parse(args ...string)error //returns error for any non-defined flags & invalid value for Int, Float64 and Bool flag.Sample Code
fc := flags.New()
fc.NewIntFlag("i", "", "Int flag name i") //set up a Int flag '-i'
fc.NewBoolFlag("verbose", "v", "Bool flag name verbose") //set up a bool flag '-verbose'
err := fc.Parse(os.Args...) //Parse() returns any error it finds during parsing
If err != nil {
fmt.Println("Parsing error:", err)
}
fmt.Println("Args:", fc.Args()) //Args() returns an array of all the arguments
fmt.Println("Verbose:", fc.Bool("verbose"))
fmt.Println("i:", fc.Int("i"))Running above
$ app arg_1 -i 100 arg_2 -verbose # run the code
Args: [arg_1 arg_2]
Verbose: true
i: 100Special function
SkipFlagParsing(bool) //if set to true, all flags become arguments
ShowUsage(leadingSpace int)string //string containing all the flags and their usage text
