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flags : handle String validation : works but getting messier all the time

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This commit is contained in:
bth 2026-01-26 20:35:58 -08:00
commit a243d3c125
1 changed files with 22 additions and 24 deletions
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46
flags/flags.go
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@ -12,7 +12,7 @@ const INTERNAL_ERR_PREFIX = "um internal err: ParseArgs"
// interface as func parameter
type Flag interface {
Set(string)
SetValid(args []string, i int) (int, bool)
Match(arg string, i, j int) bool
IsSet() bool
IsHelp() bool
@ -37,8 +37,9 @@ type Bool struct {
Help string
}
func (f *Arg) Set(val string) {
f.Val = val
func (f *Arg) SetValid(args []string, i int) (int, bool) {
f.Val = args[i]
return i, true
}
func (f *Arg) Match(arg string, i, j int) bool {
@ -53,12 +54,12 @@ func (f *Arg) IsHelp() bool {
return false
}
func (f *String) Set(val string) {
func (f *String) SetValid(args []string, i int) (int, bool) {
i, val, ok := validateIncrementFetch(args, i)
f.Val = val
return i, ok
}
// TODO: this should look ahead
// i, fetch = ValidateIncrementFetchOrExit(sub, args, i)
func (f *String) Match(arg string, _, _ int) bool {
return arg == f.Long || arg == f.Short
}
@ -71,8 +72,9 @@ func (f *String) IsHelp() bool {
return false
}
func (f *Bool) Set(_ string) {
func (f *Bool) SetValid(_ []string, i int) (int, bool) {
f.Val = true
return i, true
}
func (f *Bool) Match(arg string, _, _ int) bool {
@ -96,29 +98,21 @@ func missingValue(args []string, i int) bool {
return i+1 == len(args) || hasDashPrefix(args[i+1])
}
// if no value ahead in the args, print error and exit
func validValueOrExit(sub cmd.Subcommand, args []string, i int) {
if missingValue(args, i) {
log.Printf("um %s: %s needs a value assignment\n", sub, args[i])
log.Fatal("try: um [cmd] --help")
}
}
// 1. validate a Flag[string] by looking ahead in args, if missing, os.Exit(1)
// 1. validate a Flag[string] by looking ahead in args, if missing, return false
// 2. increment the i to skip that value and return
// 3. fetch that value and return
func validateIncrementFetchOrExit(sub cmd.Subcommand, args []string, i int) (int, string) {
func validateIncrementFetch(args []string, i int) (int, string, bool) {
if missingValue(args, i) {
log.Printf("um %s: %s needs a value assignment\n", sub, args[i])
log.Fatal("try: um [cmd] --help")
return 0, "", false
}
return i + 1, args[i+1]
return i + 1, args[i+1], true
}
// expand incoming opts struct into a []Flag
//
// WARN: incoming opts must be a pointer!
// WORB: opts struct must list its Arg types first and in expected order
// NOTE: uglier than the pretty switch statements I had per cmd, but much more convenient.
func expandOpts(opts any) []Flag {
flags := []Flag{}
v := reflect.ValueOf(opts)
@ -147,18 +141,22 @@ func expandOpts(opts any) []Flag {
}
// assign values of args to opts struct using Flag interface methods
//
// NOTE: uglier than the pretty switch statements I had per cmd, but much more convenient.
func ParseArgs(sub cmd.Subcommand, summary string, args []string, opts any) {
flags := expandOpts(opts)
argloop:
for i, arg := range args {
for i := 0; i < len(args); i++ {
arg := args[i]
for j, f := range flags {
if f.Match(arg, i, j) {
if f.IsHelp() {
Help(sub, summary, opts)
}
f.Set(arg)
ok := false
i, ok = f.SetValid(args, i)
if !ok {
log.Printf("um %s: %s needs a value assignment\n", sub, args[i])
log.Fatal("try: um [cmd] --help")
}
continue argloop
}
}