This program uses the type keyword in 2 ways: first it declares a struct type (Cat) with it, and then it sets up 2 type aliases to the Cat type. In the main() method we use the various types.
Part 1 We declare a Cat struct, and this struct has one field in it: an int field. This type declaration does not create an instance of the type.
Part 2 Here we see 2 type aliases for the Cat struct. This means the terms Kitty and Meow can be used in place of Cat.
Part 3 We use the Cat type and its 2 aliases (Kitty and Meow) to create 3 instances of the Cat type. Each cat has 4 paws.
package main
import (
"fmt"
)
// Part 1: use type to specify a new struct type.
type Cat struct {
paws int
}
// Part 2: use type to set up type aliases.
type (
Kitty = Cat
Meow = Cat
)
func main() {
// Part 3: use the struct type and its various aliased types.
c := Cat{paws: 4}
fmt.Println(c)
k := Kitty{paws: 4}
fmt.Println(k)
m := Meow{paws: 4}
fmt.Println(m)
}{4}
{4}
{4}
Summary. In Go we cannot just use the struct keyword to declare a struct—we must prefix the struct name with the type keyword. With type aliases, we can make certain programs compile correctly.
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