Remove obsolete Watch() stubs. Closes #171.

README.md

@@ -73,13 +73,12 @@ func main() {
 ```
 
 ### Watching files for changes
-The `koanf.Provider` interface has a `Watch(cb)` method that asks a provider
-to watch for changes and trigger the given callback that can live reload the
-configuration. This is not goroutine safe if there are concurrent `*Get()`
-calls happening on the koanf object while it is doing a `Load()`. Such
-scenarios will need mutex locking.
+Some providers expose a `Watch()` method that makes the provider watch for changes
+in configuration and trigger a callback to reload the configuration.
+This is not goroutine safe if there are concurrent `*Get()` calls happening on the
+koanf object while it is doing a `Load()`. Such scenarios will need mutex locking.
 
-Currently, `file.Provider` supports this.
+`file, appconfig, vault, consul` providers have a `Watch()` method.
 
 
 ```go

providers/basicflag/basicflag.go

@@ -62,8 +62,3 @@ func (p *Pflag) Read() (map[string]interface{}, error) {
 func (p *Pflag) ReadBytes() ([]byte, error) {
 	return nil, errors.New("basicflag provider does not support this method")
 }
-
-// Watch is not supported.
-func (p *Pflag) Watch(cb func(event interface{}, err error)) error {
-	return errors.New("basicflag provider does not support this method")
-}

providers/confmap/confmap.go

@@ -35,8 +35,3 @@ func (e *Confmap) ReadBytes() ([]byte, error) {
 func (e *Confmap) Read() (map[string]interface{}, error) {
 	return e.mp, nil
 }
-
-// Watch is not supported.
-func (e *Confmap) Watch(cb func(event interface{}, err error)) error {
-	return errors.New("confmap provider does not support this method")
-}

providers/env/env.go

@@ -96,8 +96,3 @@ func (e *Env) Read() (map[string]interface{}, error) {
 
 	return maps.Unflatten(mp, e.delim), nil
 }
-
-// Watch is not supported.
-func (e *Env) Watch(cb func(event interface{}, err error)) error {
-	return errors.New("env provider does not support this method")
-}

providers/fs/fs.go

@@ -2,6 +2,7 @@
 // from given fs.FS to be used with a koanf.Parser to parse
 // into conf maps.
 
+//go:build go1.16
 // +build go1.16
 
 package fs
@@ -38,8 +39,3 @@ func (f *FS) ReadBytes() ([]byte, error) {
 func (f *FS) Read() (map[string]interface{}, error) {
 	return nil, errors.New("fs.FS provider does not support this method")
 }
-
-// Watch is not supported by the fs.FS provider.
-func (f *FS) Watch(cb func(event interface{}, err error)) error {
-	return errors.New("fs.FS provider does not support this method")
-}

providers/rawbytes/rawbytes.go

@@ -29,8 +29,3 @@ func (r *RawBytes) ReadBytes() ([]byte, error) {
 func (r *RawBytes) Read() (map[string]interface{}, error) {
 	return nil, errors.New("buf provider does not support this method")
 }
-
-// Watch is not supported.
-func (r *RawBytes) Watch(cb func(event interface{}, err error)) error {
-	return errors.New("rawbytes provider does not support this method")
-}

providers/s3/s3.go

@@ -68,8 +68,3 @@ func (r *S3) ReadBytes() ([]byte, error) {
 func (r *S3) Read() (map[string]interface{}, error) {
 	return nil, errors.New("s3 provider does not support this method")
 }
-
-// Watch is not supported.
-func (r *S3) Watch(cb func(event interface{}, err error)) error {
-	return errors.New("s3 provider does not support this method")
-}

providers/structs/structs.go

@@ -46,8 +46,3 @@ func (s *Structs) Read() (map[string]interface{}, error) {
 
 	return out, nil
 }
-
-// Watch is not supported by the structs provider.
-func (s *Structs) Watch(cb func(event interface{}, err error)) error {
-	return errors.New("structs provider does not support this method")
-}