inject

package
v0.8.0 Latest Latest
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Published: Sep 26, 2018 License: Apache-2.0 Imports: 13 Imported by: 0

Documentation

Overview

Package inject implements dependency injection.

Dependency injection with the struct tag `inject:""` or the constructor.

Dependency injection in Go

Dependency injection is a concept valid for any programming language. The general concept behind dependency injection is called Inversion of Control. According to this concept a struct should not configure its dependencies statically but should be configured from the outside.

Dependency Injection design pattern allows us to remove the hard-coded dependencies and make our application loosely coupled, extendable and maintainable.

A Go struct has a dependency on another struct, if it uses an instance of this struct. We call this a struct dependency. For example, a struct which accesses a user controller has a dependency on user service struct.

Ideally Go struct should be as independent as possible from other Go struct. This increases the possibility of reusing these struct and to be able to test them independently from other struct.

The following example shows a struct which has no hard dependencies.

Example

This example shows that the dependency is injected through the constructor

Output:

Index

Examples

Constants

This section is empty.

Variables

View Source
var (
	// ErrNotImplemented the interface is not implemented
	ErrNotImplemented = errors.New("[inject] interface is not implemented")

	// ErrInvalidObject the object is invalid
	ErrInvalidObject = errors.New("[inject] invalid object")

	// ErrInvalidTagName the tag name is invalid
	ErrInvalidTagName = errors.New("[inject] invalid tag name, e.g. exampleTag")

	// ErrSystemConfiguration system is not configured
	ErrSystemConfiguration = errors.New("[inject] system is not configured")

	// ErrInvalidFunc the function is invalid
	ErrInvalidFunc = errors.New("[inject] invalid func")

	// ErrFactoryIsNil factory is invalid
	ErrFactoryIsNil = errors.New("[inject] factory is nil")
)

Functions

func AddTag added in v0.3.0

func AddTag(tag Tag)

AddTag add new tag

func DefaultValue added in v0.6.2

func DefaultValue(object interface{}) error

DefaultValue injects instance into the tagged field with `inject:"instanceName"`

func IntoFunc added in v0.6.0

func IntoFunc(object interface{}) (retVal interface{}, err error)

IntoFunc inject object into func and return instance

func IntoObject

func IntoObject(object interface{}) error

IntoObject injects instance into the tagged field with `inject:"instanceName"`

func IntoObjectValue added in v0.5.0

func IntoObjectValue(object reflect.Value, tags ...Tag) error

IntoObjectValue injects instance into the tagged field with `inject:"instanceName"`

func SetFactory added in v0.5.4

func SetFactory(f factory.ConfigurableFactory)

SetFactory set factory from app

Types

type BaseTag added in v0.3.0

type BaseTag struct {
	// contains filtered or unexported fields
}

func (*BaseTag) Decode added in v0.3.0

func (t *BaseTag) Decode(object reflect.Value, field reflect.StructField, tag string) (retVal interface{})

func (*BaseTag) Init added in v0.5.0

func (t *BaseTag) Init(systemConfig *system.Configuration, configurations cmap.ConcurrentMap)

func (*BaseTag) IsSingleton added in v0.3.0

func (t *BaseTag) IsSingleton() bool

func (*BaseTag) ParseProperties added in v0.3.0

func (t *BaseTag) ParseProperties(tag string) cmap.ConcurrentMap

func (*BaseTag) Properties added in v0.3.0

func (t *BaseTag) Properties() cmap.ConcurrentMap

type Tag added in v0.3.0

type Tag interface {
	Init(systemConfig *system.Configuration, configurations cmap.ConcurrentMap)
	Decode(object reflect.Value, field reflect.StructField, tag string) (retVal interface{})
	Properties() cmap.ConcurrentMap
	IsSingleton() bool
}

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