Remove 02.6.md spaces
This commit is contained in:
vCaesar
508
zh/02.6.md
508
zh/02.6.md
@@ -16,73 +16,73 @@ Go语言里面设计最精妙的应该算interface，它让面向对象，内容
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interface类型定义了一组方法，如果某个对象实现了某个接口的所有方法，则此对象就实现了此接口。详细的语法参考下面这个例子
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```Go
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type Human struct {
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name string
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age int
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phone string
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}
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type Human struct {
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name string
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age int
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phone string
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}
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type Student struct {
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Human //匿名字段Human
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school string
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loan float32
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}
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type Student struct {
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Human //匿名字段Human
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school string
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loan float32
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}
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type Employee struct {
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Human //匿名字段Human
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company string
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money float32
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}
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type Employee struct {
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Human //匿名字段Human
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company string
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money float32
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}
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//Human对象实现Sayhi方法
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func (h *Human) SayHi() {
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fmt.Printf("Hi, I am %s you can call me on %s\n", h.name, h.phone)
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}
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//Human对象实现Sayhi方法
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func (h *Human) SayHi() {
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fmt.Printf("Hi, I am %s you can call me on %s\n", h.name, h.phone)
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}
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// Human对象实现Sing方法
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func (h *Human) Sing(lyrics string) {
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fmt.Println("La la, la la la, la la la la la...", lyrics)
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}
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// Human对象实现Sing方法
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func (h *Human) Sing(lyrics string) {
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fmt.Println("La la, la la la, la la la la la...", lyrics)
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}
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//Human对象实现Guzzle方法
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func (h *Human) Guzzle(beerStein string) {
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fmt.Println("Guzzle Guzzle Guzzle...", beerStein)
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}
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//Human对象实现Guzzle方法
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func (h *Human) Guzzle(beerStein string) {
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fmt.Println("Guzzle Guzzle Guzzle...", beerStein)
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}
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// Employee重载Human的Sayhi方法
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func (e *Employee) SayHi() {
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fmt.Printf("Hi, I am %s, I work at %s. Call me on %s\n", e.name,
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e.company, e.phone) //此句可以分成多行
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}
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// Employee重载Human的Sayhi方法
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func (e *Employee) SayHi() {
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fmt.Printf("Hi, I am %s, I work at %s. Call me on %s\n", e.name,
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e.company, e.phone) //此句可以分成多行
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}
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//Student实现BorrowMoney方法
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func (s *Student) BorrowMoney(amount float32) {
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s.loan += amount // (again and again and...)
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}
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//Student实现BorrowMoney方法
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func (s *Student) BorrowMoney(amount float32) {
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s.loan += amount // (again and again and...)
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}
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//Employee实现SpendSalary方法
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func (e *Employee) SpendSalary(amount float32) {
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e.money -= amount // More vodka please!!! Get me through the day!
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}
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//Employee实现SpendSalary方法
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func (e *Employee) SpendSalary(amount float32) {
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e.money -= amount // More vodka please!!! Get me through the day!
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}
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// 定义interface
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type Men interface {
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SayHi()
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Sing(lyrics string)
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Guzzle(beerStein string)
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}
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// 定义interface
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type Men interface {
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SayHi()
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Sing(lyrics string)
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Guzzle(beerStein string)
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}
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type YoungChap interface {
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SayHi()
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Sing(song string)
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BorrowMoney(amount float32)
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}
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type YoungChap interface {
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SayHi()
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Sing(song string)
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BorrowMoney(amount float32)
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}
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type ElderlyGent interface {
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SayHi()
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Sing(song string)
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SpendSalary(amount float32)
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}
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type ElderlyGent interface {
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SayHi()
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Sing(song string)
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SpendSalary(amount float32)
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}
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```
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通过上面的代码我们可以知道，interface可以被任意的对象实现。我们看到上面的Men interface被Human、Student和Employee实现。同理，一个对象可以实现任意多个interface，例如上面的Student实现了Men和YoungChap两个interface。
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@@ -96,82 +96,82 @@ interface类型定义了一组方法，如果某个对象实现了某个接口
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让我们来看一下下面这个例子:
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```Go
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package main
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package main
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import "fmt"
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import "fmt"
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type Human struct {
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name string
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age int
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phone string
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type Human struct {
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name string
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age int
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phone string
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}
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type Student struct {
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Human //匿名字段
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school string
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loan float32
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}
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type Employee struct {
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Human //匿名字段
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company string
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money float32
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}
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//Human实现SayHi方法
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func (h Human) SayHi() {
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fmt.Printf("Hi, I am %s you can call me on %s\n", h.name, h.phone)
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}
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//Human实现Sing方法
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func (h Human) Sing(lyrics string) {
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fmt.Println("La la la la...", lyrics)
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}
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//Employee重载Human的SayHi方法
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func (e Employee) SayHi() {
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fmt.Printf("Hi, I am %s, I work at %s. Call me on %s\n", e.name,
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e.company, e.phone)
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}
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type Student struct {
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Human //匿名字段
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school string
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loan float32
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}
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type Employee struct {
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Human //匿名字段
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company string
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money float32
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}
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//Human实现SayHi方法
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func (h Human) SayHi() {
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fmt.Printf("Hi, I am %s you can call me on %s\n", h.name, h.phone)
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}
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//Human实现Sing方法
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func (h Human) Sing(lyrics string) {
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fmt.Println("La la la la...", lyrics)
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}
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//Employee重载Human的SayHi方法
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func (e Employee) SayHi() {
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fmt.Printf("Hi, I am %s, I work at %s. Call me on %s\n", e.name,
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e.company, e.phone)
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}
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// Interface Men被Human,Student和Employee实现
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// 因为这三个类型都实现了这两个方法
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type Men interface {
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SayHi()
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Sing(lyrics string)
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}
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func main() {
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mike := Student{Human{"Mike", 25, "222-222-XXX"}, "MIT", 0.00}
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paul := Student{Human{"Paul", 26, "111-222-XXX"}, "Harvard", 100}
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sam := Employee{Human{"Sam", 36, "444-222-XXX"}, "Golang Inc.", 1000}
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tom := Employee{Human{"Tom", 37, "222-444-XXX"}, "Things Ltd.", 5000}
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//定义Men类型的变量i
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var i Men
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//i能存储Student
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i = mike
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fmt.Println("This is Mike, a Student:")
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i.SayHi()
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i.Sing("November rain")
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//i也能存储Employee
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i = tom
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fmt.Println("This is tom, an Employee:")
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i.SayHi()
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i.Sing("Born to be wild")
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//定义了slice Men
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fmt.Println("Let's use a slice of Men and see what happens")
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x := make([]Men, 3)
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//这三个都是不同类型的元素，但是他们实现了interface同一个接口
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x[0], x[1], x[2] = paul, sam, mike
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for _, value := range x{
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value.SayHi()
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}
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// Interface Men被Human,Student和Employee实现
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// 因为这三个类型都实现了这两个方法
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type Men interface {
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SayHi()
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Sing(lyrics string)
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}
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func main() {
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mike := Student{Human{"Mike", 25, "222-222-XXX"}, "MIT", 0.00}
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paul := Student{Human{"Paul", 26, "111-222-XXX"}, "Harvard", 100}
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sam := Employee{Human{"Sam", 36, "444-222-XXX"}, "Golang Inc.", 1000}
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tom := Employee{Human{"Tom", 37, "222-444-XXX"}, "Things Ltd.", 5000}
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//定义Men类型的变量i
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var i Men
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//i能存储Student
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i = mike
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fmt.Println("This is Mike, a Student:")
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i.SayHi()
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i.Sing("November rain")
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//i也能存储Employee
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i = tom
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fmt.Println("This is tom, an Employee:")
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i.SayHi()
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i.Sing("Born to be wild")
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//定义了slice Men
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fmt.Println("Let's use a slice of Men and see what happens")
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x := make([]Men, 3)
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//这三个都是不同类型的元素，但是他们实现了interface同一个接口
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x[0], x[1], x[2] = paul, sam, mike
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for _, value := range x{
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value.SayHi()
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}
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}
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```
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通过上面的代码，你会发现interface就是一组抽象方法的集合，它必须由其他非interface类型实现，而不能自我实现， Go通过interface实现了duck-typing:即"当看到一只鸟走起来像鸭子、游泳起来像鸭子、叫起来也像鸭子，那么这只鸟就可以被称为鸭子"。
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@@ -179,13 +179,13 @@ interface类型定义了一组方法，如果某个对象实现了某个接口
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空interface(interface{})不包含任何的method，正因为如此，所有的类型都实现了空interface。空interface对于描述起不到任何的作用(因为它不包含任何的method），但是空interface在我们需要存储任意类型的数值的时候相当有用，因为它可以存储任意类型的数值。它有点类似于C语言的void*类型。
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```Go
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// 定义a为空接口
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var a interface{}
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var i int = 5
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s := "Hello world"
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// a可以存储任意类型的数值
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a = i
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a = s
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// 定义a为空接口
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var a interface{}
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var i int = 5
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s := "Hello world"
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// a可以存储任意类型的数值
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a = i
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a = s
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```
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一个函数把interface{}作为参数，那么他可以接受任意类型的值作为参数，如果一个函数返回interface{},那么也就可以返回任意类型的值。是不是很有用啊！
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### interface函数参数
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@@ -194,41 +194,41 @@ interface的变量可以持有任意实现该interface类型的对象，这给
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举个例子：fmt.Println是我们常用的一个函数，但是你是否注意到它可以接受任意类型的数据。打开fmt的源码文件，你会看到这样一个定义:
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```Go
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type Stringer interface {
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String() string
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}
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type Stringer interface {
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String() string
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}
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```
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也就是说，任何实现了String方法的类型都能作为参数被fmt.Println调用,让我们来试一试
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```Go
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package main
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import (
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"fmt"
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"strconv"
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)
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package main
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import (
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"fmt"
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"strconv"
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)
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type Human struct {
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name string
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age int
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phone string
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}
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type Human struct {
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name string
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age int
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phone string
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}
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// 通过这个方法 Human 实现了 fmt.Stringer
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func (h Human) String() string {
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return "❰"+h.name+" - "+strconv.Itoa(h.age)+" years - ✆ " +h.phone+"❱"
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}
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// 通过这个方法 Human 实现了 fmt.Stringer
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func (h Human) String() string {
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return "❰"+h.name+" - "+strconv.Itoa(h.age)+" years - ✆ " +h.phone+"❱"
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}
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func main() {
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Bob := Human{"Bob", 39, "000-7777-XXX"}
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fmt.Println("This Human is : ", Bob)
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}
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func main() {
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Bob := Human{"Bob", 39, "000-7777-XXX"}
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fmt.Println("This Human is : ", Bob)
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}
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```
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现在我们再回顾一下前面的Box示例，你会发现Color结构也定义了一个method：String。其实这也是实现了fmt.Stringer这个interface，即如果需要某个类型能被fmt包以特殊的格式输出，你就必须实现Stringer这个接口。如果没有实现这个接口，fmt将以默认的方式输出。
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```Go
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//实现同样的功能
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fmt.Println("The biggest one is", boxes.BiggestsColor().String())
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fmt.Println("The biggest one is", boxes.BiggestsColor())
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//实现同样的功能
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fmt.Println("The biggest one is", boxes.BiggestsColor().String())
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fmt.Println("The biggest one is", boxes.BiggestsColor())
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```
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注：实现了error接口的对象（即实现了Error() string的对象），使用fmt输出时，会调用Error()方法，因此不必再定义String()方法了。
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### interface变量存储的类型
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@@ -244,44 +244,44 @@ interface的变量可以持有任意实现该interface类型的对象，这给
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让我们通过一个例子来更加深入的理解。
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```Go
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package main
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package main
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import (
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"fmt"
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"strconv"
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)
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import (
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"fmt"
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"strconv"
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)
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type Element interface{}
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type List [] Element
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type Element interface{}
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type List [] Element
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type Person struct {
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name string
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age int
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}
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type Person struct {
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name string
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age int
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}
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//定义了String方法，实现了fmt.Stringer
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func (p Person) String() string {
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return "(name: " + p.name + " - age: "+strconv.Itoa(p.age)+ " years)"
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}
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//定义了String方法，实现了fmt.Stringer
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func (p Person) String() string {
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return "(name: " + p.name + " - age: "+strconv.Itoa(p.age)+ " years)"
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}
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func main() {
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list := make(List, 3)
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list[0] = 1 // an int
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list[1] = "Hello" // a string
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list[2] = Person{"Dennis", 70}
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func main() {
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list := make(List, 3)
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list[0] = 1 // an int
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list[1] = "Hello" // a string
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list[2] = Person{"Dennis", 70}
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for index, element := range list {
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if value, ok := element.(int); ok {
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fmt.Printf("list[%d] is an int and its value is %d\n", index, value)
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} else if value, ok := element.(string); ok {
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fmt.Printf("list[%d] is a string and its value is %s\n", index, value)
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} else if value, ok := element.(Person); ok {
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fmt.Printf("list[%d] is a Person and its value is %s\n", index, value)
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} else {
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fmt.Printf("list[%d] is of a different type\n", index)
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}
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for index, element := range list {
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if value, ok := element.(int); ok {
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fmt.Printf("list[%d] is an int and its value is %d\n", index, value)
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} else if value, ok := element.(string); ok {
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fmt.Printf("list[%d] is a string and its value is %s\n", index, value)
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} else if value, ok := element.(Person); ok {
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fmt.Printf("list[%d] is a Person and its value is %s\n", index, value)
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} else {
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fmt.Printf("list[%d] is of a different type\n", index)
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}
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}
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}
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```
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是不是很简单啊，同时你是否注意到了多个if里面，还记得我前面介绍流程时讲过，if里面允许初始化变量。
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|
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@@ -291,45 +291,45 @@ interface的变量可以持有任意实现该interface类型的对象，这给
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最好的讲解就是代码例子，现在让我们重写上面的这个实现
|
||||
```Go
|
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|
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package main
|
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package main
|
||||
|
||||
import (
|
||||
"fmt"
|
||||
"strconv"
|
||||
)
|
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import (
|
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"fmt"
|
||||
"strconv"
|
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)
|
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|
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type Element interface{}
|
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type List [] Element
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type Element interface{}
|
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type List [] Element
|
||||
|
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type Person struct {
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name string
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age int
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}
|
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type Person struct {
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name string
|
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age int
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}
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|
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//打印
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func (p Person) String() string {
|
||||
return "(name: " + p.name + " - age: "+strconv.Itoa(p.age)+ " years)"
|
||||
}
|
||||
//打印
|
||||
func (p Person) String() string {
|
||||
return "(name: " + p.name + " - age: "+strconv.Itoa(p.age)+ " years)"
|
||||
}
|
||||
|
||||
func main() {
|
||||
list := make(List, 3)
|
||||
list[0] = 1 //an int
|
||||
list[1] = "Hello" //a string
|
||||
list[2] = Person{"Dennis", 70}
|
||||
func main() {
|
||||
list := make(List, 3)
|
||||
list[0] = 1 //an int
|
||||
list[1] = "Hello" //a string
|
||||
list[2] = Person{"Dennis", 70}
|
||||
|
||||
for index, element := range list{
|
||||
switch value := element.(type) {
|
||||
case int:
|
||||
fmt.Printf("list[%d] is an int and its value is %d\n", index, value)
|
||||
case string:
|
||||
fmt.Printf("list[%d] is a string and its value is %s\n", index, value)
|
||||
case Person:
|
||||
fmt.Printf("list[%d] is a Person and its value is %s\n", index, value)
|
||||
default:
|
||||
fmt.Println("list[%d] is of a different type", index)
|
||||
}
|
||||
for index, element := range list{
|
||||
switch value := element.(type) {
|
||||
case int:
|
||||
fmt.Printf("list[%d] is an int and its value is %d\n", index, value)
|
||||
case string:
|
||||
fmt.Printf("list[%d] is a string and its value is %s\n", index, value)
|
||||
case Person:
|
||||
fmt.Printf("list[%d] is a Person and its value is %s\n", index, value)
|
||||
default:
|
||||
fmt.Println("list[%d] is of a different type", index)
|
||||
}
|
||||
}
|
||||
}
|
||||
```
|
||||
这里有一点需要强调的是：`element.(type)`语法不能在switch外的任何逻辑里面使用，如果你要在switch外面判断一个类型就使用`comma-ok`。
|
||||
|
||||
@@ -339,33 +339,33 @@ Go里面真正吸引人的是它内置的逻辑语法，就像我们在学习Str
|
||||
我们可以看到源码包container/heap里面有这样的一个定义
|
||||
```Go
|
||||
|
||||
type Interface interface {
|
||||
sort.Interface //嵌入字段sort.Interface
|
||||
Push(x interface{}) //a Push method to push elements into the heap
|
||||
Pop() interface{} //a Pop elements that pops elements from the heap
|
||||
}
|
||||
type Interface interface {
|
||||
sort.Interface //嵌入字段sort.Interface
|
||||
Push(x interface{}) //a Push method to push elements into the heap
|
||||
Pop() interface{} //a Pop elements that pops elements from the heap
|
||||
}
|
||||
```
|
||||
我们看到sort.Interface其实就是嵌入字段，把sort.Interface的所有method给隐式的包含进来了。也就是下面三个方法：
|
||||
```Go
|
||||
|
||||
type Interface interface {
|
||||
// Len is the number of elements in the collection.
|
||||
Len() int
|
||||
// Less returns whether the element with index i should sort
|
||||
// before the element with index j.
|
||||
Less(i, j int) bool
|
||||
// Swap swaps the elements with indexes i and j.
|
||||
Swap(i, j int)
|
||||
}
|
||||
type Interface interface {
|
||||
// Len is the number of elements in the collection.
|
||||
Len() int
|
||||
// Less returns whether the element with index i should sort
|
||||
// before the element with index j.
|
||||
Less(i, j int) bool
|
||||
// Swap swaps the elements with indexes i and j.
|
||||
Swap(i, j int)
|
||||
}
|
||||
```
|
||||
另一个例子就是io包下面的 io.ReadWriter ，它包含了io包下面的Reader和Writer两个interface：
|
||||
```Go
|
||||
|
||||
// io.ReadWriter
|
||||
type ReadWriter interface {
|
||||
Reader
|
||||
Writer
|
||||
}
|
||||
// io.ReadWriter
|
||||
type ReadWriter interface {
|
||||
Reader
|
||||
Writer
|
||||
}
|
||||
```
|
||||
### 反射
|
||||
Go语言实现了反射，所谓反射就是能检查程序在运行时的状态。我们一般用到的包是reflect包。如何运用reflect包，官方的这篇文章详细的讲解了reflect包的实现原理，[laws of reflection](http://golang.org/doc/articles/laws_of_reflection.html)
|
||||
@@ -373,38 +373,38 @@ Go语言实现了反射，所谓反射就是能检查程序在运行时的状态
|
||||
使用reflect一般分成三步，下面简要的讲解一下：要去反射是一个类型的值(这些值都实现了空interface)，首先需要把它转化成reflect对象(reflect.Type或者reflect.Value，根据不同的情况调用不同的函数)。这两种获取方式如下：
|
||||
```Go
|
||||
|
||||
t := reflect.TypeOf(i) //得到类型的元数据,通过t我们能获取类型定义里面的所有元素
|
||||
v := reflect.ValueOf(i) //得到实际的值，通过v我们获取存储在里面的值，还可以去改变值
|
||||
t := reflect.TypeOf(i) //得到类型的元数据,通过t我们能获取类型定义里面的所有元素
|
||||
v := reflect.ValueOf(i) //得到实际的值，通过v我们获取存储在里面的值，还可以去改变值
|
||||
```
|
||||
转化为reflect对象之后我们就可以进行一些操作了，也就是将reflect对象转化成相应的值，例如
|
||||
```Go
|
||||
|
||||
tag := t.Elem().Field(0).Tag //获取定义在struct里面的标签
|
||||
name := v.Elem().Field(0).String() //获取存储在第一个字段里面的值
|
||||
tag := t.Elem().Field(0).Tag //获取定义在struct里面的标签
|
||||
name := v.Elem().Field(0).String() //获取存储在第一个字段里面的值
|
||||
```
|
||||
获取反射值能返回相应的类型和数值
|
||||
```Go
|
||||
|
||||
var x float64 = 3.4
|
||||
v := reflect.ValueOf(x)
|
||||
fmt.Println("type:", v.Type())
|
||||
fmt.Println("kind is float64:", v.Kind() == reflect.Float64)
|
||||
fmt.Println("value:", v.Float())
|
||||
var x float64 = 3.4
|
||||
v := reflect.ValueOf(x)
|
||||
fmt.Println("type:", v.Type())
|
||||
fmt.Println("kind is float64:", v.Kind() == reflect.Float64)
|
||||
fmt.Println("value:", v.Float())
|
||||
```
|
||||
最后，反射的话，那么反射的字段必须是可修改的，我们前面学习过传值和传引用，这个里面也是一样的道理。反射的字段必须是可读写的意思是，如果下面这样写，那么会发生错误
|
||||
```Go
|
||||
|
||||
var x float64 = 3.4
|
||||
v := reflect.ValueOf(x)
|
||||
v.SetFloat(7.1)
|
||||
var x float64 = 3.4
|
||||
v := reflect.ValueOf(x)
|
||||
v.SetFloat(7.1)
|
||||
```
|
||||
如果要修改相应的值，必须这样写
|
||||
```Go
|
||||
|
||||
var x float64 = 3.4
|
||||
p := reflect.ValueOf(&x)
|
||||
v := p.Elem()
|
||||
v.SetFloat(7.1)
|
||||
var x float64 = 3.4
|
||||
p := reflect.ValueOf(&x)
|
||||
v := p.Elem()
|
||||
v.SetFloat(7.1)
|
||||
```
|
||||
上面只是对反射的简单介绍，更深入的理解还需要自己在编程中不断的实践。
|
||||
|
||||
|
||||
Reference in New Issue
Block a user