inject

README

Inject

This package provides the dependency injection with Go.

Example

Please refer to example

Documentation

Overview

Package inject provides a reflect based injector. A large application built with dependency injection in mind will typically involve the boring work of setting up the object graph. This library attempts to take care of this boring work by creating and connecting the various objects. Its use involves you seeding the object graph with some (possibly incomplete) objects, where the underlying types have been tagged for injection. Given this, the library will populate the objects creating new ones as necessary. It uses singletons by default, supports optional private instances as well as named instances.

It works using Go's reflection package and is inherently limited in what it can do as opposed to a code-gen system with respect to private fields.

The usage pattern for the library involves struct tags. It requires the tag format used by the various standard libraries, like json, xml etc. It involves tags in one of the three forms below:

`inject:""`
`inject:"private"`
`inject:"dev logger"`

The first no value syntax is for the common case of a singleton dependency of the associated type. The second triggers creation of a private instance for the associated type. Finally the last form is asking for a named dependency called "dev logger".

Index

• func Populate(values ...interface{}) error
• type Graph
  • func (g *Graph) Objects() []*Object
  • func (g *Graph) Populate() error
  • func (g *Graph) Provide(objects ...*Object) error
• type Logger
• type Object
  • func (o *Object) String() string

Functions

func Populate

func Populate(values ...interface{}) error

Populate is a short-hand for populating a graph with the given incomplete object values.

Types

type Graph

type Graph struct {
	Logger Logger // Optional, will trigger debug logging.
	// contains filtered or unexported fields
}

The Graph of Objects.

func (*Graph) Objects

func (g *Graph) Objects() []*Object

Objects returns all known objects, named as well as unnamed. The returned elements are not in a stable order.

func (*Graph) Populate

func (g *Graph) Populate() error

Populate the incomplete Objects.

func (*Graph) Provide

func (g *Graph) Provide(objects ...*Object) error

Provide objects to the Graph. The Object documentation describes the impact of various fields.

type Logger

type Logger interface {
	Debugf(format string, v ...interface{})
}

Logger allows for simple logging as inject traverses and populates the object graph.

type Object

type Object struct {
	Value    interface{}
	Name     string             // Optional
	Complete bool               // If true, the Value will be considered complete
	Fields   map[string]*Object // Populated with the field names that were injected and their corresponding *Object.
	// contains filtered or unexported fields
}

An Object in the Graph.

func (*Object) String

func (o *Object) String() string

String representation suitable for human consumption.