gointerface is an interface extractor for Go.
To install gointerface, just use the following command:
go install github.com/yeefea/gointerface@latestUsage of gointerface:
-i string
Input file or directory. By default, the program reads from stdin.
-o string
Output file. By default, the program writes content to stdout.
-p string
Rewrite the package name in the output.
-private
Include private methods.
-t string
Specify the types. Multiple types are separated by comma(,). Extract all types if not specified.
For example, let's create a file example.go and define a few types as follows:
package example
import (
"fmt"
"strings"
j "encoding/json"
)
type SomeStruct struct{}
/*
Some block comments.
*/
// ToJson converts the object to json bytes.
// some other comments
func (x *SomeStruct) ToJson(sb strings.Builder) ([]byte, error) {
return j.Marshal([]string{"1", "2", "3"})
}
// ComplexMethod is a complex method.
func (s *SomeStruct) ComplexMethod(c, d *map[string]int) (f1, f2 func(
*map[string]int, *map[string]int), x *map[string]int, y *map[string]int) {
return nil, nil, nil, nil
}
// privateMethod is a private method.
func (x *SomeStruct) privateMethod(sb strings.Builder) ([]byte, error) {
return j.Marshal([]string{"1", "2", "3"})
}
type IntArray []int
// Desc describes the array.
func (arr *IntArray) Desc() {
fmt.Println(arr)
}To read from a Go file and print the interfaces to stdout, use the following command:
gointerface -i example.goThe interfaces will be extracted from the source code, with the package statement, the import statements and the comments preserved.
// Code generated from gointerface
package example
import (
j "encoding/json"
"fmt"
"strings"
)
type IIntArray interface {
// Desc describes the array.
Desc()
}
type ISomeStruct interface {
// ComplexMethod is a complex method.
ComplexMethod(c, d *map[string]int) (f1, f2 func(
*map[string]int, *map[string]int), x *map[string]int, y *map[string]int)
/*
Some block comments.
*/
// ToJson converts the object to json bytes.
// some other comments
ToJson(sb strings.Builder) ([]byte, error)
}By default, gointerface writes the output to stdout. To write the output to a file, use the -o option:
gointerface -i example.go -o interface.goThe program will write the output to interface.go.
Private methods, which start with a lower case letter, are not extracted by default. To extract private methods, use the -private option:
gointerface -i example.go -privateThen the private method privateMethod will included in the output interface.
type ISomeStruct interface {
// ComplexMethod is a complex method.
ComplexMethod(c, d *map[string]int) (f1, f2 func(
*map[string]int, *map[string]int), x *map[string]int, y *map[string]int)
/*
Some block comments.
*/
// ToJson converts the object to json bytes.
// some other comments
ToJson(sb strings.Builder) ([]byte, error)
// privateMethod is a private method.
privateMethod(sb strings.Builder) ([]byte, error)
}Let's create a new directory example and put the example.go file in it. Then create a new file example2.go in that directory. Now we have the following directory structure:
└── example
├── example.go
└── example2.go
Use -i option to specify the package:
gointerface -i exampleThe program will analyze all go files in the example directory and extract the interfaces.
A method can have both receivers and pointer receivers. For example, the following struct:
// example2.go
package example
type MixedReceiver struct{}
func (r *MixedReceiver) PointerReceiver() {}
func (r MixedReceiver) ValueReceiver() {}If a struct have methods with both receivers and pointer receivers, gointerface will generate two interfaces for it. One interface corresponds to the pointer receiver methods and is named I{TypeName}. The other interface corresponds to the value receiver methods and is named I{TypeName}Value. The above example will have the following two interfaces:
// Code generated from gointerface
package example
type IMixedReceiver interface {
PointerReceiver()
}
type IMixedReceiverValue interface {
ValueReceiver()
}