From 63a14d4df55d328e6e17cff5b68ab86f1cb55330 Mon Sep 17 00:00:00 2001 From: Christopher Hargarten Date: Thu, 19 Sep 2019 08:18:51 -0500 Subject: [PATCH] set usage message from description tag (#70) set usage message in flags backend from description tag --- README.md | 6 ++++-- backend/flags/flags.go | 31 ++++++++++++++++++------------- config.go | 20 +++++++++++++------- 3 files changed, 35 insertions(+), 22 deletions(-) diff --git a/README.md b/README.md index 6807a87..ceb73b6 100644 --- a/README.md +++ b/README.md @@ -161,11 +161,13 @@ The `flags` backend allows to load individual configuration keys from the comman A `short` option is also supported. +To update usage message on the command line, provide a `description` to the given field. + ```go type Config struct { Host string `config:"host,short=h"` Port uint32 `config:"port,short=p"` - Timeout time.Duration `config:"timeout"` + Timeout time.Duration `config:"timeout,description=timeout (in seconds) for failure"` } ``` @@ -183,7 +185,7 @@ Usage of ./bin: -p int (default 5656) -timeout duration - (default 10s) + timeout (in seconds) for failure (default 10s) ``` ## License diff --git a/backend/flags/flags.go b/backend/flags/flags.go index a28d354..68f3e66 100644 --- a/backend/flags/flags.go +++ b/backend/flags/flags.go @@ -3,6 +3,7 @@ package flags import ( "context" "flag" + "fmt" "reflect" "time" @@ -33,9 +34,9 @@ func (b *Backend) LoadStruct(ctx context.Context, cfg *confita.StructConfig) err switch { case f.Value.Type().String() == "time.Duration": var val time.Duration - flag.DurationVar(&val, f.Key, time.Duration(f.Default.Int()), "") + flag.DurationVar(&val, f.Key, time.Duration(f.Default.Int()), f.Description) if f.Short != "" { - flag.DurationVar(&val, f.Short, time.Duration(f.Default.Int()), "") + flag.DurationVar(&val, f.Short, time.Duration(f.Default.Int()), shortDesc(f.Description)) } // this function must be executed after the flag.Parse call. defer func() { @@ -46,9 +47,9 @@ func (b *Backend) LoadStruct(ctx context.Context, cfg *confita.StructConfig) err }() case k == reflect.Bool: var val bool - flag.BoolVar(&val, f.Key, f.Default.Bool(), "") + flag.BoolVar(&val, f.Key, f.Default.Bool(), f.Description) if f.Short != "" { - flag.BoolVar(&val, f.Short, f.Default.Bool(), "") + flag.BoolVar(&val, f.Short, f.Default.Bool(), shortDesc(f.Description)) } defer func() { if isFlagSet(f) { @@ -57,9 +58,9 @@ func (b *Backend) LoadStruct(ctx context.Context, cfg *confita.StructConfig) err }() case k >= reflect.Int && k <= reflect.Int64: var val int - flag.IntVar(&val, f.Key, int(f.Default.Int()), "") + flag.IntVar(&val, f.Key, int(f.Default.Int()), f.Description) if f.Short != "" { - flag.IntVar(&val, f.Short, int(f.Default.Int()), "") + flag.IntVar(&val, f.Short, int(f.Default.Int()), shortDesc(f.Description)) } defer func() { if isFlagSet(f) { @@ -68,9 +69,9 @@ func (b *Backend) LoadStruct(ctx context.Context, cfg *confita.StructConfig) err }() case k >= reflect.Uint && k <= reflect.Uint64: var val uint64 - flag.Uint64Var(&val, f.Key, f.Default.Uint(), "") + flag.Uint64Var(&val, f.Key, f.Default.Uint(), f.Description) if f.Short != "" { - flag.Uint64Var(&val, f.Short, f.Default.Uint(), "") + flag.Uint64Var(&val, f.Short, f.Default.Uint(), shortDesc(f.Description)) } defer func() { if isFlagSet(f) { @@ -79,9 +80,9 @@ func (b *Backend) LoadStruct(ctx context.Context, cfg *confita.StructConfig) err }() case k >= reflect.Float32 && k <= reflect.Float64: var val float64 - flag.Float64Var(&val, f.Key, f.Default.Float(), "") + flag.Float64Var(&val, f.Key, f.Default.Float(), f.Description) if f.Short != "" { - flag.Float64Var(&val, f.Short, f.Default.Float(), "") + flag.Float64Var(&val, f.Short, f.Default.Float(), shortDesc(f.Description)) } defer func() { if isFlagSet(f) { @@ -90,9 +91,9 @@ func (b *Backend) LoadStruct(ctx context.Context, cfg *confita.StructConfig) err }() case k == reflect.String: var val string - flag.StringVar(&val, f.Key, f.Default.String(), "") + flag.StringVar(&val, f.Key, f.Default.String(), f.Description) if f.Short != "" { - flag.StringVar(&val, f.Short, f.Default.String(), "") + flag.StringVar(&val, f.Short, f.Default.String(), shortDesc(f.Description)) } defer func() { if isFlagSet(f) { @@ -100,7 +101,7 @@ func (b *Backend) LoadStruct(ctx context.Context, cfg *confita.StructConfig) err } }() default: - flag.Var(&flagValue{f}, f.Key, "") + flag.Var(&flagValue{f}, f.Key, f.Description) } } @@ -135,6 +136,10 @@ func (b *Backend) Name() string { return "flags" } +func shortDesc(description string) string { + return fmt.Sprintf("%s (short)", description) +} + func isFlagSet(config *confita.FieldConfig) bool { flagset := make(map[*confita.FieldConfig]bool) flag.Visit(func(f *flag.Flag) { flagset[config] = true }) diff --git a/config.go b/config.go index 0f9651c..f004228 100644 --- a/config.go +++ b/config.go @@ -137,6 +137,11 @@ func (l *Loader) parseStruct(ref reflect.Value) *StructConfig { continue } + if strings.HasPrefix(opt, "description=") { + f.Description = opt[len("description="):] + continue + } + if strings.HasPrefix(opt, "backend=") { f.Backend = opt[len("backend="):] } @@ -242,13 +247,14 @@ type StructConfig struct { // FieldConfig holds informations about a struct field. type FieldConfig struct { - Name string - Short string - Key string - Value reflect.Value - Default reflect.Value - Required bool - Backend string + Name string + Short string + Key string + Description string + Value reflect.Value + Default reflect.Value + Required bool + Backend string } // Set converts data into f.Value.