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README

do - Dependency Injection

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⚙️ A dependency injection toolkit based on Go 1.18+ Generics.

This library implements the Dependency Injection design pattern. It may replace the uber/dig fantastic package. samber/do uses Go 1.18+ generics instead of reflection and therefore offers a typesafe API.

See also:

  • samber/lo: A Lodash-style Go library based on Go 1.18+ Generics
  • samber/mo: Monads based on Go 1.18+ Generics (Option, Result, Either...)

Why this name?

I love the short name for such a utility library. This name is the sum of DI and Go and no Go package uses this name.

🔥 Migration from v1 to v2

Documentation here

💡 Features

  • 📒 Service registration
    • By type inference
    • By name
  • 🪃 Service invocation
    • Eager loading
    • Lazy loading
    • Transient loading
  • 🧙‍♂️ Service aliasing
    • Implicit (provide struct, invoke interface)
    • Explicit (provide struct, bind interface, invoke interface)
  • 🔁 Service lifecycle
    • Health check
    • Graceful unload (shutdown)
    • Lifecycle hooks
  • 📦 Scope (a.k.a module) tree
    • Visibility control
    • Dependency grouping
  • 📤 Injector
    • Dependency graph resolution and visualization
    • Default injector
    • Injector cloning
    • Service override
  • 🌈 Lightweight, no dependencies
  • 🔅 No code generation
  • 😷 Typesafe API

🚀 Install

# v2 (latest)
go get github.com/samber/do@v2

# v1
go get github.com/samber/do

This library is v2 and follows SemVer strictly.

No breaking changes will be made to exported APIs before v3.0.0.

This library has no dependencies except the Go std lib.

🤠 Documentation

🛩 Benchmark

// @TODO

🤝 Contributing

Don't hesitate ;)

# Install some dev dependencies
make tools

# Run tests
make test
# or
make watch-test

👤 Contributors

Contributors

💫 Show your support

Give a ⭐️ if this project helped you!

GitHub Sponsors

📝 License

Copyright © 2022 Samuel Berthe.

This project is MIT licensed.

Documentation

Index

Examples

Constants

View Source 
const DefaultRootScopeName = "[root]"

Variables

View Source 
var ErrCircularDependency = errors.New("DI: circular dependency detected")
View Source 
var ErrHealthCheckTimeout = errors.New("DI: health check timeout")
View Source 
var ErrServiceNotFound = errors.New("DI: could not find service")

Functions

func As 

func As[Initial any, Alias any](i Injector) error

As declares an alias for a service.

func AsNamed 

func AsNamed[Initial any, Alias any](i Injector, initial string, alias string) error

AsNamed declares a named alias for a named service.

func DescribeInjector 

func DescribeInjector(scope Injector) (output string, ok bool)

DescribeInjector returns a human readable description of the injector, with services and scope tree.

func DescribeNamedService 

func DescribeNamedService[T any](scope Injector, name string) (output string, ok bool)

DescribeNamedService returns a human readable description of the service. It returns false if the service is not found. Please call Invoke[T] before DescribeNamedService[T] to ensure that the service is registered.

func DescribeService 

func DescribeService[T any](i Injector) (output string, ok bool)

DescribeService returns a human readable description of the service. It returns false if the service is not found. Please call Invoke[T] before DescribeService[T] to ensure that the service is registered.

func ExampleInjector_Clone 

func ExampleInjector_Clone()

func ExampleInjector_HealthCheck 

func ExampleInjector_HealthCheck()

func ExampleInjector_ListInvokedServices_invoked 

func ExampleInjector_ListInvokedServices_invoked()

func ExampleInjector_ListInvokedServices_notInvoked 

func ExampleInjector_ListInvokedServices_notInvoked()

func ExampleInjector_ListProvidedServices 

func ExampleInjector_ListProvidedServices()

func ExampleInjector_Shutdown 

func ExampleInjector_Shutdown()

func ExplainNamedService 

func ExplainNamedService(scope Injector, name string) (dependencies []EdgeService, dependents []EdgeService, ok bool)

ExplainNamedService returns a list of dependencies and dependents of a named service.

func ExplainService 

func ExplainService[T any](scope Injector) (dependencies []EdgeService, dependents []EdgeService, ok bool)

ExplainService returns a list of dependencies and dependents of a service.

func HealthCheck 

func HealthCheck[T any](i Injector) error

HealthCheck returns a service status, using type inference to determine the service name.

func HealthCheckNamed 

func HealthCheckNamed(i Injector, name string) error

HealthCheckNamed returns a service status.

func HealthCheckNamedWithContext 

func HealthCheckNamedWithContext(ctx context.Context, i Injector, name string) error

HealthCheckNamedWithContext returns a service status.

func HealthCheckWithContext 

func HealthCheckWithContext[T any](ctx context.Context, i Injector) error

HealthCheckWithContext returns a service status, using type inference to determine the service name.

func Invoke 

func Invoke[T any](i Injector) (T, error)

Invoke invokes a service in the DI container, using type inference to determine the service name.

Example 
injector := New()

type test struct {
	foobar string
}

Provide(injector, func(i Injector) (*test, error) {
	return &test{foobar: "foobar"}, nil
})
value, err := Invoke[*test](injector)

fmt.Println(value)
fmt.Println(err)

Output:

&{foobar}
<nil>

func InvokeAs 

func InvokeAs[T any](i Injector) (T, error)

InvokeAs invokes a service in the DI container. The first service matching the provided type or interface will be invoked.

func InvokeNamed 

func InvokeNamed[T any](i Injector, name string) (T, error)

InvokeNamed invokes a named service in the DI container.

Example 
injector := New()

type test struct {
	foobar string
}

ProvideNamed(injector, "my_service", func(i Injector) (*test, error) {
	return &test{foobar: "foobar"}, nil
})
value, err := InvokeNamed[*test](injector, "my_service")

fmt.Println(value)
fmt.Println(err)

Output:

&{foobar}
<nil>

func MustAs 

func MustAs[Initial any, Alias any](i Injector)

MustAs declares an alias for a service. It panics on error.

func MustAsNamed 

func MustAsNamed[Initial any, Alias any](i Injector, initial string, alias string)

AsNamed declares a named alias for a named service. It panics on error.

func MustInvoke 

func MustInvoke[T any](i Injector) T

MustInvoke invokes a service in the DI container, using type inference to determine the service name. It panics on error.

Example 
injector := New()

type test struct {
	foobar string
}

Provide(injector, func(i Injector) (*test, error) {
	return &test{foobar: "foobar"}, nil
})
value := MustInvoke[*test](injector)

fmt.Println(value)

Output:

&{foobar}

func MustInvokeAs 

func MustInvokeAs[T any](i Injector) T

MustInvokeAs invokes a service in the DI container. The first service matching the provided type or interface will be invoked. It panics on error.

func MustInvokeNamed 

func MustInvokeNamed[T any](i Injector, name string) T

MustInvokeNamed invokes a named service in the DI container. It panics on error.

Example 
injector := New()

type test struct {
	foobar string
}

ProvideNamed(injector, "my_service", func(i Injector) (*test, error) {
	return &test{foobar: "foobar"}, nil
})
value := MustInvokeNamed[*test](injector, "my_service")

fmt.Println(value)

Output:

&{foobar}

func MustShutdown 

func MustShutdown[T any](i Injector)

MustShutdown stops a service, using type inference to determine the service name. It panics on error.

func MustShutdownNamed 

func MustShutdownNamed(i Injector, name string)

MustShutdownNamed stops a named service. It panics on error.

func MustShutdownNamedWithContext 

func MustShutdownNamedWithContext(ctx context.Context, i Injector, name string)

MustShutdownNamedWithContext stops a named service. It panics on error.

func MustShutdownWithContext 

func MustShutdownWithContext[T any](ctx context.Context, i Injector)

MustShutdownWithContext stops a service, using type inference to determine the service name. It panics on error.

func NameOf 

func NameOf[T any]() string

NameOf returns the name of the service in the DI container. This is higly discouraged to use this function, as your code should not declare any dependency explicitly.

func Override 

func Override[T any](i Injector, provider Provider[T])

Override replaces the service in the DI container, using type inference to determine the service name.

Example 
injector := New()

type test struct {
	foobar string
}

Provide(injector, func(i Injector) (*test, error) {
	return &test{foobar: "foobar1"}, nil
})
Override(injector, func(i Injector) (*test, error) {
	return &test{foobar: "foobar2"}, nil
})
value, err := Invoke[*test](injector)

fmt.Println(value)
fmt.Println(err)

Output:

&{foobar2}
<nil>

func OverrideNamed 

func OverrideNamed[T any](i Injector, name string, provider Provider[T])

OverrideNamed replaces the named service in the DI container.

Example 
injector := New()

type test struct {
	foobar string
}

ProvideNamed(injector, "my_service", func(i Injector) (*test, error) {
	return &test{foobar: "foobar1"}, nil
})
OverrideNamed(injector, "my_service", func(i Injector) (*test, error) {
	return &test{foobar: "foobar2"}, nil
})
value, err := InvokeNamed[*test](injector, "my_service")

fmt.Println(value)
fmt.Println(err)

Output:

&{foobar2}
<nil>

func OverrideNamedTransient 

func OverrideNamedTransient[T any](i Injector, name string, provider Provider[T])

OverrideNamedTransient replaces the named factory in the DI container.

func OverrideNamedValue 

func OverrideNamedValue[T any](i Injector, name string, value T)

OverrideNamedValue replaces the named value in the DI container.

Example 
injector := New()

type test struct {
	foobar string
}

ProvideNamedValue(injector, "my_service", &test{foobar: "foobar1"})
OverrideNamedValue(injector, "my_service", &test{foobar: "foobar2"})
value, err := InvokeNamed[*test](injector, "my_service")

fmt.Println(value)
fmt.Println(err)

Output:

&{foobar2}
<nil>

func OverrideTransient 

func OverrideTransient[T any](i Injector, provider Provider[T])

OverrideTransient replaces the factory in the DI container, using type inference to determine the service name.

func OverrideValue 

func OverrideValue[T any](i Injector, value T)

OverrideValue replaces the value in the DI container, using type inference to determine the service name.

func Provide 

func Provide[T any](i Injector, provider Provider[T])

Provide registers a service in the DI container, using type inference.

Example 
injector := New()

type test struct {
	foobar string
}

Provide(injector, func(i Injector) (*test, error) {
	return &test{foobar: "foobar"}, nil
})
value, err := Invoke[*test](injector)

fmt.Println(value)
fmt.Println(err)

Output:

&{foobar}
<nil>

func ProvideNamed 

func ProvideNamed[T any](i Injector, name string, provider Provider[T])

ProvideNamed registers a named service in the DI container.

Example 
injector := New()

type test struct {
	foobar string
}

ProvideNamed(injector, "my_service", func(i Injector) (*test, error) {
	return &test{foobar: "foobar"}, nil
})
value, err := InvokeNamed[*test](injector, "my_service")

fmt.Println(value)
fmt.Println(err)

Output:

&{foobar}
<nil>

func ProvideNamedTransient 

func ProvideNamedTransient[T any](i Injector, name string, provider Provider[T])

ProvideNamedTransient registers a named factory in the DI container.

func ProvideNamedValue 

func ProvideNamedValue[T any](i Injector, name string, value T)

ProvideNamedValue registers a named value in the DI container.

Example 
injector := New()

type test struct {
	foobar string
}

ProvideNamedValue(injector, "my_service", &test{foobar: "foobar"})
value, err := InvokeNamed[*test](injector, "my_service")

fmt.Println(value)
fmt.Println(err)

Output:

&{foobar}
<nil>

func ProvideTransient 

func ProvideTransient[T any](i Injector, provider Provider[T])

ProvideTransient registers a factory in the DI container, using type inference to determine the service name.

func ProvideValue 

func ProvideValue[T any](i Injector, value T)

ProvideValue registers a value in the DI container, using type inference to determine the service name.

Example 
injector := New()

type test struct {
	foobar string
}

ProvideValue(injector, &test{foobar: "foobar"})
value, err := Invoke[*test](injector)

fmt.Println(value)
fmt.Println(err)

Output:

&{foobar}
<nil>

func Shutdown 

func Shutdown[T any](i Injector) error

Shutdown stops a service, using type inference to determine the service name.

func ShutdownNamed 

func ShutdownNamed(i Injector, name string) error

ShutdownNamed stops a named service.

func ShutdownNamedWithContext 

func ShutdownNamedWithContext(ctx context.Context, i Injector, name string) error

ShutdownNamedWithContext stops a named service.

func ShutdownWithContext 

func ShutdownWithContext[T any](ctx context.Context, i Injector) error

ShutdownWithContext stops a service, using type inference to determine the service name.

Types

type DAG 

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

DAG represents a Directed Acyclic Graph of services, tracking dependencies and dependents.

type EdgeService 

type EdgeService struct {
	ScopeID   string
	ScopeName string
	Service   string
}

EdgeService represents a service in the DAG, identified by scope ID, scope name, and service name.

type Healthchecker 

type Healthchecker interface {
	HealthCheck() error
}

type HealthcheckerWithContext 

type HealthcheckerWithContext interface {
	HealthCheck(context.Context) error
}

type Injector 

type Injector interface {
	// api
	ID() string
	Name() string
	Scope(string) *Scope
	RootScope() *RootScope
	Ancestors() []*Scope
	Children() []*Scope
	ChildByID(string) (*Scope, bool)
	ChildByName(string) (*Scope, bool)
	ListProvidedServices() []EdgeService
	ListInvokedServices() []EdgeService
	HealthCheck() map[string]error
	HealthCheckWithContext(context.Context) map[string]error
	Shutdown() error
	ShutdownWithContext(context.Context) error
	// contains filtered or unexported methods
}

Injector is a DI container.

type InjectorOpts 

type InjectorOpts struct {
	HookAfterRegistration func(scope *Scope, serviceName string)
	HookAfterShutdown     func(scope *Scope, serviceName string)

	Logf func(format string, args ...any)

	HealthCheckParallelism   uint          // default: all jobs are executed in parallel
	HealthCheckGlobalTimeout time.Duration // default: no timeout
	HealthCheckTimeout       time.Duration // default: no timeout
}

type Provider 

type Provider[T any] func(Injector) (T, error)

type RootScope 

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

RootScope is the first level of scope tree. 

var DefaultRootScope *RootScope = New()

func New 

func New() *RootScope

New creates a new injector.

func NewWithOpts 

func NewWithOpts(opts *InjectorOpts) *RootScope

NewWithOpts creates a new injector with options.

func (*RootScope) Ancestors 

func (s *RootScope) Ancestors() []*Scope

func (*RootScope) ChildByID 

func (s *RootScope) ChildByID(id string) (*Scope, bool)

func (*RootScope) ChildByName 

func (s *RootScope) ChildByName(name string) (*Scope, bool)

func (*RootScope) Children 

func (s *RootScope) Children() []*Scope

func (*RootScope) Clone 

func (s *RootScope) Clone() *RootScope

Clone clones injector with provided services but not with invoked instances.

func (*RootScope) CloneWithOpts 

func (s *RootScope) CloneWithOpts(opts *InjectorOpts) *RootScope

CloneWithOpts clones injector with provided services but not with invoked instances, with options.

func (*RootScope) HealthCheck 

func (s *RootScope) HealthCheck() map[string]error

func (*RootScope) HealthCheckWithContext 

func (s *RootScope) HealthCheckWithContext(ctx context.Context) map[string]error

func (*RootScope) ID 

func (s *RootScope) ID() string

pass through

func (*RootScope) ListInvokedServices 

func (s *RootScope) ListInvokedServices() []EdgeService

func (*RootScope) ListProvidedServices 

func (s *RootScope) ListProvidedServices() []EdgeService

func (*RootScope) Name 

func (s *RootScope) Name() string

func (*RootScope) RootScope 

func (s *RootScope) RootScope() *RootScope

func (*RootScope) Scope 

func (s *RootScope) Scope(name string) *Scope

func (*RootScope) Shutdown 

func (s *RootScope) Shutdown() error

func (*RootScope) ShutdownOnSIGTERM 

func (s *RootScope) ShutdownOnSIGTERM() (os.Signal, error)

ShutdownOnSIGTERM listens for sigterm signal in order to graceful stop service. It will block until receiving a sigterm signal.

func (*RootScope) ShutdownOnSIGTERMOrInterrupt 

func (s *RootScope) ShutdownOnSIGTERMOrInterrupt() (os.Signal, error)

ShutdownOnSIGTERMOrInterrupt listens for sigterm or interrupt signal in order to graceful stop service. It will block until receiving a sigterm signal.

func (*RootScope) ShutdownOnSIGTERMOrInterruptWithContext 

func (s *RootScope) ShutdownOnSIGTERMOrInterruptWithContext(ctx context.Context) (os.Signal, error)

ShutdownOnSIGTERMOrInterruptWithContext listens for sigterm or interrupt signal in order to graceful stop service. It will block until receiving a sigterm signal.

func (*RootScope) ShutdownOnSIGTERMWithContext 

func (s *RootScope) ShutdownOnSIGTERMWithContext(ctx context.Context) (os.Signal, error)

ShutdownOnSIGTERMWithContext listens for sigterm signal in order to graceful stop service. It will block until receiving a sigterm signal.

func (*RootScope) ShutdownOnSignals 

func (s *RootScope) ShutdownOnSignals(signals ...os.Signal) (os.Signal, error)

ShutdownOnSignals listens for signals defined in signals parameter in order to graceful stop service. It will block until receiving any of these signal. If no signal is provided in signals parameter, syscall.SIGTERM will be added as default signal.

func (*RootScope) ShutdownOnSignalsWithContext 

func (s *RootScope) ShutdownOnSignalsWithContext(ctx context.Context, signals ...os.Signal) (os.Signal, error)

ShutdownOnSignalsWithContext listens for signals defined in signals parameter in order to graceful stop service. It will block until receiving any of these signal. If no signal is provided in signals parameter, syscall.SIGTERM will be added as default signal.

func (*RootScope) ShutdownWithContext 

func (s *RootScope) ShutdownWithContext(ctx context.Context) error

type Scope 

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

Scope is a DI container. It must be created with injector.Scope("name") method.

func (*Scope) Ancestors 

func (s *Scope) Ancestors() []*Scope

Ancestors returns the list of parent scopes recursively.

func (*Scope) ChildByID 

func (s *Scope) ChildByID(id string) (*Scope, bool)

ChildByID returns the child scope recursively by its ID.

func (*Scope) ChildByName 

func (s *Scope) ChildByName(name string) (*Scope, bool)

ChildByName returns the child scope recursively by its name.

func (*Scope) Children 

func (s *Scope) Children() []*Scope

Children returns the list of immediate child scopes.

func (*Scope) HealthCheck 

func (s *Scope) HealthCheck() map[string]error

HealthCheck returns the healthcheck results of the scope, in a map of service name to error.

func (*Scope) HealthCheckWithContext 

func (s *Scope) HealthCheckWithContext(ctx context.Context) map[string]error

HealthCheckWithContext returns the healthcheck results of the scope, in a map of service name to error.

func (*Scope) ID 

func (s *Scope) ID() string

ID returns the unique identifier of the scope.

func (*Scope) ListInvokedServices 

func (s *Scope) ListInvokedServices() []EdgeService

ListInvokedServices returns the list of services invoked by the scope.

func (*Scope) ListProvidedServices 

func (s *Scope) ListProvidedServices() []EdgeService

ListProvidedServices returns the list of services provided by the scope.

func (*Scope) Name 

func (s *Scope) Name() string

Name returns the name of the scope.

func (*Scope) RootScope 

func (s *Scope) RootScope() *RootScope

RootScope returns the root scope.

func (*Scope) Scope 

func (s *Scope) Scope(name string) *Scope

Scope creates a new child scope.

func (*Scope) Shutdown 

func (s *Scope) Shutdown() error

Shutdown shutdowns the scope and all its children.

func (*Scope) ShutdownWithContext 

func (s *Scope) ShutdownWithContext(ctx context.Context) error

ShutdownWithContext shutdowns the scope and all its children.

type Service 

type Service[T any] interface {
	// contains filtered or unexported methods
}

type ServiceAlias 

type ServiceAlias[Initial any, Alias any] struct {
	// contains filtered or unexported fields
}

type ServiceEager 

type ServiceEager[T any] struct {
	// contains filtered or unexported fields
}

type ServiceLazy 

type ServiceLazy[T any] struct {
	// contains filtered or unexported fields
}

type ServiceTransient 

type ServiceTransient[T any] struct {
	// contains filtered or unexported fields
}

type ServiceType 

type ServiceType string
const (
	ServiceTypeLazy      ServiceType = "lazy"
	ServiceTypeEager     ServiceType = "eager"
	ServiceTypeTransient ServiceType = "transient"
	ServiceTypeAlias     ServiceType = "alias"
)

type Shutdowner 

type Shutdowner interface {
	Shutdown()
}

type ShutdownerWithContext 

type ShutdownerWithContext interface {
	Shutdown(context.Context)
}

type ShutdownerWithContextAndError 

type ShutdownerWithContextAndError interface {
	Shutdown(context.Context) error
}

type ShutdownerWithError 

type ShutdownerWithError interface {
	Shutdown() error
}

Source Files

View all Source files

Directories

Path Synopsis
examples
dag command
healthcheckable command
interface command
nested-scope command
shutdownable command
simple command

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