TypeRegistry is a generic system to instantiate types by name. Since go cannot instantiate a type directly, we must first register any type that we would later like to instantiate. The registry handles these mechanics for you.
In addition, the registry supports marshal, unmarshal, and custom setup for getting objects in and out of storage.
To use, create a registry, then register add any types to it. Make sure to add the pointer receiver if that's what you want to instantiate.
// The type you'd like to instantiate by name.
type simpleThing struct { }
// A registry.
registry := typeregistry.New()
// Register a type, this one by pointer receiver.
name := registry.Add(&simpleThing{})
// Get a *simpleThing
thing := registry.New(name)See this example file for more detailed examples of marshal, unmarshal and custom setup.
A common pattern for using this library is as a global handler to marshal/unmarshal a specific type. Here, implementations of a fictional Conversation type can be registered and then pulled in and out of storage formats. The package-level wrapper functions perform the typecasting needed to keep things simple for users.
package main
import "github.com/rcarver/typeregistry"
// Conversation is implemented many different ways.
type Conversation interface {
Talk()
}
var registry = typeregistry.New()
// Register adds a new type to the conversation registry.
func Register(c Conversation) {
registry.Add(c)
}
// Marshal encodes the conversation, returning its registered name, and the
// encoded bytes.
func Marshal(c Conversation) (string, []byte, error) {
return registry.Marshal(c)
}
// ConvoSetupFunc is used to setup a conversation before it's unmarshaled.
type ConvoSetupFunc func(Conversation)
// Unmarshal decodes a conversation.
func Unmarshal(name string, data []byte, setup ConvoSetupFunc) (Conversation, error) {
o, err := registry.Unmarshal(name, data, func(o interface{}) {
if setup != nil {
setup(o.(Conversation))
}
})
if err == nil {
return o.(Conversation), nil
}
return nil, err
}Ryan Carver (ryan@ryancarver.com)
MIT