Impl

Generates or sync implement of interface type, and methods of interface to implements in specify filepath.

Exist methods signature would be synced, and missing methods would be appended in file.

Usage

Annotation

+zz:impl:[filename][:options...]

Annotation Target

Object interface

Exact Arguments

filename

File or directory of implement type.

If filepath do not ends with .go provided, use impl.go as default filename.

Example: +zz:impl:./impls/type.go

Optional Arguments

type

Specify implement type name.

Add * prefix if pointer receiver were desired. Default: *${interface name}Impl

Example: +zz:impl:./impls:type=*Impl

wire

Add wire plugin annotation when generating implement type: +zz:wire:bind=${interface name}.

It has no effect if implement type exist.

Example: +zz:impl:./impls:wire

aop

Add aop option on wire annotations, should be used with wire.

It has no effect if implement type exist or wire were not used.

Example: +zz:impl:./impls:wire:aop

Examples

Example-01

Example Project (opens new window)

/impl01/
├── go.mod -> module github.com/go-zing/gozz-doc-examples/impl01
├── implements
│   └── impl.go
└── types.go

package impl01

//go:generate gozz run -p "impl" ./

// +zz:impl:./implements
type ReadCloser interface {
	Read(b []byte) (int, error)
	Close() error
}

We got ReadCloserImpl in impl01/implements/impl.go. But contains only Read.

package implements

type ReadCloserImpl struct{}

func (impl *ReadCloserImpl) Read() (int, error) {
	return len(b), nil
}

Execute gozz run -p "impl" ./.

Plugin would lookup implement type named ReadCloserImpl in impl01/implements. And collect class methods of this implement type.

After comparing existing class methods and interface methods, class method's signatures would be sync with same name interface method, and those that do not exist would be supplemented.

Example: Read would be synced as interface defined. And Close that missing before were appended.

package implements

type ReadCloserImpl struct{}

func (impl *ReadCloserImpl) Read(b []byte) (int, error) {
	return len(b), nil
}

func (impl *ReadCloserImpl) Close() error {
	panic("not implemented")
}

Example-02

Example Project (opens new window)

/impl02/
├── go.mod -> module github.com/go-zing/gozz-doc-examples/impl02
└── types.go

package impl02

//go:generate gozz run -p "impl" ./

// +zz:impl:./implements:type=Impl:wire
type ReadCloser interface {
	Read(b []byte) (int, error)
	Close() error
}

Execute gozz run -p "impl" ./.

Directory implements were generated. Also Impl type and methods were generated in ./implements/impl.go.

• Annotation for wire plugin were added because option wire.
• Methods would not have pointer receiver because option type=Impl does not start with *.

package implements

import impl02 "github.com/go-zing/gozz-doc-examples/impl02"

var (
	_ impl02.ReadCloser = (*Impl)(nil)
)

// +zz:wire:bind=impl02.ReadCloser
type Impl struct{}

func (impl Impl) Read(b []byte) (int, error) {
	panic("not implemented")
}

func (impl Impl) Close() error {
	panic("not implemented")
}

Example-03

Example Project (opens new window)

/impl03/
├── go.mod -> module github.com/go-zing/gozz-doc-examples/impl03
├── implements
│   └── impl.go
└── types.go

package impl03

//go:generate gozz run -p "impl" ./

// +zz:impl:./implements:type=Impl:wire
type ReadCloser interface {
	Read(b []byte) (int, error)
	Close() error
}

File ./implements/impl.go exists, and contains type ReadCloserImpl and method Read.

package implements

type ReadCloserImpl struct{}

func (impl *ReadCloserImpl) Read() {}

Because we had specified type name type=*Impl, it would not have any effects to type ReadCloserImpl.

Execute gozz run -p "impl" ./, and generate struct Impl and class methods in ./implements/impl.go, using pointer receiver and annotations with option wire aop.

package implements

import "github.com/go-zing/gozz-doc-examples/impl03"

type ReadCloserImpl struct{}

func (impl *ReadCloserImpl) Read() {}

var (
	_ impl03.ReadCloser = (*Impl)(nil)
)

// +zz:wire:bind=impl03.ReadCloser
type Impl struct{}

func (impl Impl) Read(b []byte) (int, error) {
	panic("not implemented")
}

func (impl Impl) Close() error {
	panic("not implemented")
}

Example-04

Example Project (opens new window)

/impl04/
├── go.mod -> module github.com/go-zing/gozz-doc-examples/impl04
├── implements
│   └── read.go
└── types.go

package impl04

//go:generate gozz run -p "impl" ./

// +zz:impl:./implements
type ReadCloser interface {
	Read(b []byte) (int, error)
	Close() error
}

File ./implements/read.go exists, contains type Impl and its method Read.

package implements

type ReadCloserImpl struct{}

func (impl *ReadCloserImpl) Read() (int, error) {
	return 0, nil
}

Execute gozz run -p "impl" ./,

Method Read in ./implements/read.go were synced.

package implements

type ReadCloserImpl struct{}

func (impl *ReadCloserImpl) Read(b []byte) (int, error) {
	return 0, nil
}

File ./implements/impl.go generated, with method Close.

package implements

func (impl *ReadCloserImpl) Close() error {
	panic("not implemented")
}