# Gone's Hook Functions

# What are Hook Functions?

In the process of starting and stopping Gone, support is provided to register four types of functions that will be executed at specific times, known as Hook functions:

  • BeforeStart Hook function: Executes before Gone starts, registered using BeforeStart.
  • AfterStart Hook function: Executes after Gone starts, registered using AfterStart.
  • BeforeStop Hook function: Executes before Gone stops, registered using BeforeStop.
  • AfterStop Hook function: Executes after Gone stops, registered using AfterStop.

# Code Example

package main
import "github.com/gone-io/gone"
type Worker struct {
	Name string
type Boss struct {
	Name string
func main() {
		Prepare(func(cemetery gone.Cemetery) error {
			cemetery.Bury(&Boss{Name: "Jim"}, "boss-jim")
			cemetery.Bury(&Worker{Name: "Bob"}, "worker-bob")
			return nil
		BeforeStart(func() {
			println("First BeforeStart function")
		BeforeStart(func(in struct {
			worker Worker `gone:"worker-bob"`
			boss   Boss   `gone:"*"`
		}) {
			println("Second BeforeStart function")
			println("Boss:", in.boss.Name)
			println("Worker:", in.worker.Name)
		BeforeStart(func() error {
			println("Third BeforeStart function")
			return nil

The output of the above code is as follows:

Third BeforeStart function
Second BeforeStart function
Boss: Jim
Worker: Bob
First BeforeStart function

# Rules for Hook Functions

  1. Multiple registrations of the same type of Hook function are allowed.
  2. For BeforeStart and BeforeStop Hook functions, the ones registered later are executed first.
  3. For AfterStart and AfterStop Hook functions, the ones registered earlier are executed first.
  4. Hook functions can be registered using the Preparer object returned by gone.Prepare(priest), supporting chaining.
  5. The types of functions that can be registered with the Preparer object include:
    • Input Parameters:
      • No parameters
      • Anonymous struct parameters, with properties annotated with gone tags automatically injected with corresponding values.
    • Return Parameters:
      • No return parameters
      • error parameter; if the error parameter is not nil, the program will panic when it reaches the Hook, terminating execution.

# Gone's Startup Process

  1. Revive all buried Goners.
  2. Execute the AfterRevive method of all prophet Goners.
  3. Register the Start method of angels as BeforeStart Hook functions and the Stop method as BeforeStop Hook functions.
  4. Register Hook functions for business code.
  5. Execute BeforeStart Hook functions in order.
  6. Execute AfterStart Hook functions in order.
  7. Wait for the program to end.
  8. Execute BeforeStop Hook functions in order.
  9. Execute AfterStop Hook functions in order.