Using extract and inline refactorings

Extract a variable

1. Select and right-click the following code fragment: &User{ ID: 1, Name: "Smith",}.

2. Navigate to Refactor | Extract | Variable.

3. Type u as a name for a new variable.

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

1. Select and right-click the following code fragment: &User{ ID: 1, Name: "Smith",}.

2. Navigate to Refactor | Extract | Method.

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

1. In the editor, select an expression or declaration of a variable you want to replace with a constant.

2. Press Ctrl+Alt+C to introduce a constant or select Refactor | Extract | Constant.

   note

   By default, GoLand uses the in-place refactoring. To use the dialog for the refactoring, open the Settings/Preferences dialog (Ctrl+Alt+S), go to Editor | Code Editing, and select the In modal dialogs refactoring option in the Refactorings area.

3. 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.

Code snippet at GitHub

Extract functions and methods

1. 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.

2. Press Ctrl+Alt+M or from the main menu, select Refactor | Extract | Extract Method.

3. Type a method name and press Enter.

Gif

Code snippet at GitHub