Using extract and inline refactorings

With extract and inline refactorings, you can quickly clean up your code and make it more streamlined or explicit.

Extract a variable

Select and right-click the following code fragment: &User{ ID: 1, Name: "Smith",}.
Navigate to Refactor | Extract | Variable.
Type u as a name for a new variable.

Code snippet

package main

import (
	"errors"
	"fmt"
	"log"
)

type User struct {
	ID   int
	Name string
}

func findUser(user string) (*User, error) {
	if user != "smith" {
		return nil, errors.New("user not found")
	}
	return &User{
		ID:   1,
		Name: "Smith",
	}, nil
}

func main() {
	user, err := findUser("smith")
	if err != nil {
		log.Fatalf("could not find user %s\n", "smith")
	}

	fmt.Printf("user found: %#v\n", user)
}

Extract methods

Select and right-click the following code fragment: &User{ ID: 1, Name: "Smith",}.
Navigate to Refactor | Extract | Method.

Code snippet

package main

import "fmt"

type rect struct {
	width, height int
}

func main() {
	r := rect{width: 10, height: 5}
	perim := 2*r.width + 2*r.height
	area := r.width * r.height
	fmt.Println("area: ", area)
	fmt.Println("perim: ", perim)
}

            

Extract a constant

In the editor, select an expression or declaration of a variable you want to replace with a constant.
Press Ctrl+Alt+C to introduce a constant or select Refactor | Extract | Constant.

Select an expression you want to extract as constant and press Enter. Select the number of occurrences you want to replace and a name you want to use.

The in-place refactoring is available by default, you can control it through the Enable in-place mode checkbox that is located in Settings/Preferences | Editor | General (scroll down to the Refactorings section).

If you clear this checkbox, GoLand will use the Extract Constant dialog for this refactoring.

Code snippet

                   package main

                   import "fmt"

                   func plus(a int, b int) int {
                   return a + b
                   }

                   func plusPlus(a, b, c int) int {
                   return a + b + c
                   }

                   func main() {
                   res := plus(1, 2)
                   fmt.Println("1+2+3·=", res)

                   res = plusPlus(1, 2, 3)
                   fmt.Println("1+2+3·=", res)
                   }
               

Extract a function or a method

In the editor, select an expression or its part that you want to extract. You can also position the caret within the expression, in this case GoLand offers you a list of potential code selections.
Press Ctrl+Alt+M or on the main menu, select Refactor | Extract | Extract Method.
Type a method name and press Enter.

Example of the Extract a method refactoring

Code snippet

                package main

                import "fmt"

                type rect struct {
                width, height int
                }

                func main() {
                r := rect{width: 10, height: 5}
                perim := 2*r.width + 2*r.height
                area := r.width * r.height
                fmt.Println("area: ", area)
                fmt.Println("perim:", perim)

                }
            

Last modified: 17 May 2019