Goの構造体のフィールドに関数を埋め込んでDIを実現してみる ref: https://qiita.com/Sekky0905/items/be5d83674a1aa78a397a

file0.go

package main

import (
    "fmt"
)

type Hoge struct {
}

func (h *Hoge) Foo(bar string) string {
    return fmt.Sprintf("%sだ!", bar)
}

func main() {
    h := &Hoge{}

    fmt.Println(h.Foo("sekky0905"))
}

file1.txt

sekky0905だ!

file2.go

// A struct with 6 fields.
struct {
    x, y int
    u float32
    _ float32  // padding
    A *[]int
    F func()
}

file3.go

import "fmt"

type Hoge struct {
    Foo func(bar string) string
}

func main() {
    f := func(bar string) string {
        return fmt.Sprintf("%sだ!", bar)
    }

    h := &Hoge{Foo: f}

    fmt.Println(h.Foo("sekky0905"))
}

file4.txt

sekky0905だ!

file5.go

package main

import (
    "fmt"
)

type Strategy interface {
    ExecuteStrategy()
}

type StrategyA struct {
    Name string
}

func (s *StrategyA) ExecuteStrategy() {
    fmt.Printf("%s実行したぜ~!\n", s.Name)
}

func NewStrategyA(name string) Strategy {
    return &StrategyA{
        Name: name,
    }
}

type StrategyB struct {
    Name string
}

func (s *StrategyB) ExecuteStrategy() {
    fmt.Printf("%s実行したよ~!\n", s.Name)
}

func NewStrategyB(name string) Strategy {
    return &StrategyB{
        Name: name,
    }
}

type Player struct {
    Strategy Strategy // Strategy型にすることで、後で埋め込む際にStrategy型を実装した任意の型を埋め込むことができる
}

func main() {
    sa := NewStrategyA("StrategyA")
    p1 := &Player{
        Strategy: sa,
    }

    p1.Strategy.ExecuteStrategy()

    sb := NewStrategyB("StrategyB")
    p2 := &Player{
        Strategy: sb,
    }

    p2.Strategy.ExecuteStrategy()
}

file6.txt

StrategyA実行したぜ~!
StrategyB実行したよ~!

file7.go

package main

import (
    "fmt"
)

type Player struct {
    ExecuteStrategy func(name string)
}

func ExecuteStrategyA(name string) {
    fmt.Printf("%s実行したぜ~!\n", name)
}

func ExecuteStrategyB(name string) {
    fmt.Printf("%s実行したよ~!\n", name)
}

func main() {
    p1 := &Player{
        ExecuteStrategy: ExecuteStrategyA,
    }
    p1.ExecuteStrategy("StrategyA")

    p2 := &Player{
        ExecuteStrategy: ExecuteStrategyB,
    }
    p2.ExecuteStrategy("StrategyB")
}

file8.txt

StrategyA実行したぜ~!
StrategyB実行したよ~!