Add OnFinalize method (#1788)

This method is the OnInitialize counterpart. Like OnInitialize which allows
loading the configuration before each command is executed, OnFinalize allows
saving the configuration after each command has been executed.

cobra.go

@@ -40,6 +40,7 @@ var templateFuncs = template.FuncMap{
 }
 
 var initializers []func()
+var finalizers []func()
 
 const (
 	defaultPrefixMatching  = false
@@ -94,6 +95,12 @@ func OnInitialize(y ...func()) {
 	initializers = append(initializers, y...)
 }
 
+// OnFinalize sets the passed functions to be run when each command's
+// Execute method is terminated.
+func OnFinalize(y ...func()) {
+	finalizers = append(finalizers, y...)
+}
+
 // FIXME Gt is unused by cobra and should be removed in a version 2. It exists only for compatibility with users of cobra.
 
 // Gt takes two types and checks whether the first type is greater than the second. In case of types Arrays, Chans,

command.go

@@ -834,6 +834,8 @@ func (c *Command) execute(a []string) (err error) {
 
 	c.preRun()
 
+	defer c.postRun()
+
 	argWoFlags := c.Flags().Args()
 	if c.DisableFlagParsing {
 		argWoFlags = a
@@ -904,6 +906,12 @@ func (c *Command) preRun() {
 	}
 }
 
+func (c *Command) postRun() {
+	for _, x := range finalizers {
+		x()
+	}
+}
+
 // ExecuteContext is the same as Execute(), but sets the ctx on the command.
 // Retrieve ctx by calling cmd.Context() inside your *Run lifecycle or ValidArgs
 // functions.