Files
app/module.go
2025-06-03 16:58:33 -07:00

82 lines
2.0 KiB
Go

package app
import (
"errors"
"fmt"
"log/slog"
"strings"
)
// ErrModuleNotFound is returned when a module is not found in the lifecycle.
var ErrModuleNotFound = errors.New("module not found")
// moduleFn is a function type for module setup and teardown functions.
type moduleFn func(*Module) error
// Module represents a sub-system of the application, with its setup and
// teardown functions and dependencies.
type Module struct {
logger *slog.Logger
name string
setup moduleFn
teardown moduleFn
depends []string
loaded bool // loaded indicates if the module has been set up
}
// ModuleOpts contains user-exposed options when defining a module.
type ModuleOpts struct {
// Setup is the setup function for the module.
Setup moduleFn
// Teardown is the teardown function for the module.
Teardown moduleFn
// Depends is a list of modules that this module depends on. Each entry must
// be the exact name of a module registered in the lifecycle.
Depends []string
}
// NewModule creates a new Module instance with the given name and options.
func NewModule(name string, opts ModuleOpts) *Module {
return &Module{
name: name,
setup: opts.Setup,
teardown: opts.Teardown,
depends: opts.Depends,
}
}
// Logger returns the logger for the module.
func (s *Module) Logger() *slog.Logger {
if s.logger == nil {
panic(fmt.Sprintf("module %s used before logger was initialized", s.name))
}
return s.logger
}
// Name returns the name of the module.
func (s *Module) Name() string {
return s.name
}
// Loaded returns whether the module has been set up.
func (s *Module) Loaded() bool {
return s.loaded
}
// RequireLoaded panics if the module is not loaded. Any arguments are included
// in the panic message for additional context.
func (s *Module) RequireLoaded(msg ...string) {
ctx := ""
if len(msg) > 0 {
ctx = ": " + strings.Join(msg, ", ")
}
if s == nil {
panic("module is nil" + ctx)
}
if !s.loaded {
panic(fmt.Sprintf("module %s not loaded", s.name) + ctx)
}
}