Documentation
¶
Overview ¶
Package positional implements parsing positional arguments, for example command line arguments, into fields of a struct.
Example ¶
package main
import (
"fmt"
"bazil.org/bazil/cliutil/positional"
)
func main() {
type Inventory struct {
Item string
positional.Optional
Count int
}
porch := Inventory{}
err := positional.Parse(&porch, []string{"cat", "3"})
if err != nil {
fmt.Println("error:", err)
return
}
fmt.Printf("You have %d %s(s) on the porch\n", porch.Count, porch.Item)
house := Inventory{
Count: 1,
}
err = positional.Parse(&house, []string{"dog"})
if err != nil {
fmt.Println("error:", err)
return
}
fmt.Printf("You have %d %s(s) in the house\n", house.Count, house.Item)
}
Output: You have 3 cat(s) on the porch You have 1 dog(s) in the house
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Parse ¶
Parse fills the fields of the struct pointed to by args with input from the given list.
Fields are handled based on their data type, for example strings are converted into integers when necessary.
In addition to built-in conversion rules, if a field implements Setter, the Set method is called to do the conversion. This interface is compatible with flag.Value.
To mark fields optional, insert an Optional marker in the struct after the last mandatory field.
To consume any number of arguments, use a slice as the last field.
Parse returns an error of type ErrMissingMandatoryArg if a mandatory field was not filled.
Parse returns an error of type ErrTooManyArgs if there are more arguments than (non-slice) fields.
func Usage ¶
func Usage(args interface{}) string
Usage returns a string suitable for use in a command line synopsis.
Struct tags with the key "positional" can be used to control the usage message. The following struct tags are supported:
- "metavar": meta variable name to use, defaults to field name in upper case
Example ¶
package main
import (
"fmt"
"bazil.org/bazil/cliutil/positional"
)
func main() {
var args struct {
Op string `positional:",metavar=ACTION"`
positional.Optional
Path []string
}
usage := positional.Usage(&args)
fmt.Printf("Usage: doit [-v] %s\n", usage)
}
Output: Usage: doit [-v] ACTION [PATH..]
Types ¶
type ErrMissingMandatoryArg ¶
type ErrMissingMandatoryArg struct {
Name string
}
ErrMissingMandatoryArg indicates that a mandatory argument is missing.
func (ErrMissingMandatoryArg) Error ¶
func (e ErrMissingMandatoryArg) Error() string
type ErrTooManyArgs ¶
type ErrTooManyArgs struct{}
ErrTooManyArgs indicates that there were too many arguments.
func (ErrTooManyArgs) Error ¶
func (ErrTooManyArgs) Error() string
Source Files