Remove 02.5.md spaces
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vCaesar
330
zh/02.5.md
330
zh/02.5.md
@@ -5,24 +5,24 @@
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现在假设有这么一个场景，你定义了一个struct叫做长方形，你现在想要计算他的面积，那么按照我们一般的思路应该会用下面的方式来实现
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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 Rectangle struct {
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width, height float64
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}
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type Rectangle struct {
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width, height float64
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}
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func area(r Rectangle) float64 {
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return r.width*r.height
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}
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func area(r Rectangle) float64 {
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return r.width*r.height
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}
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func main() {
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r1 := Rectangle{12, 2}
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r2 := Rectangle{9, 4}
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fmt.Println("Area of r1 is: ", area(r1))
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fmt.Println("Area of r2 is: ", area(r2))
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}
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func main() {
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r1 := Rectangle{12, 2}
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r2 := Rectangle{9, 4}
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fmt.Println("Area of r1 is: ", area(r1))
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fmt.Println("Area of r2 is: ", area(r2))
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}
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```
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这段代码可以计算出来长方形的面积，但是area()不是作为Rectangle的方法实现的（类似面向对象里面的方法），而是将Rectangle的对象（如r1,r2）作为参数传入函数计算面积的。
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@@ -53,41 +53,41 @@ method的语法如下：
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下面我们用最开始的例子用method来实现：
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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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"math"
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)
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import (
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"fmt"
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"math"
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)
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type Rectangle struct {
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width, height float64
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}
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type Rectangle struct {
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width, height float64
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}
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type Circle struct {
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radius float64
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}
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type Circle struct {
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radius float64
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}
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func (r Rectangle) area() float64 {
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return r.width*r.height
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}
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func (r Rectangle) area() float64 {
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return r.width*r.height
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}
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func (c Circle) area() float64 {
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return c.radius * c.radius * math.Pi
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}
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func (c Circle) area() float64 {
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return c.radius * c.radius * math.Pi
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}
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func main() {
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r1 := Rectangle{12, 2}
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r2 := Rectangle{9, 4}
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c1 := Circle{10}
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c2 := Circle{25}
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func main() {
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r1 := Rectangle{12, 2}
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r2 := Rectangle{9, 4}
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c1 := Circle{10}
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c2 := Circle{25}
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fmt.Println("Area of r1 is: ", r1.area())
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fmt.Println("Area of r2 is: ", r2.area())
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fmt.Println("Area of c1 is: ", c1.area())
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fmt.Println("Area of c2 is: ", c2.area())
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}
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fmt.Println("Area of r1 is: ", r1.area())
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fmt.Println("Area of r2 is: ", r2.area())
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fmt.Println("Area of c1 is: ", c1.area())
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fmt.Println("Area of c2 is: ", c2.area())
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}
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```
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@@ -110,23 +110,23 @@ method的语法如下：
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那是不是method只能作用在struct上面呢？当然不是咯，他可以定义在任何你自定义的类型、内置类型、struct等各种类型上面。这里你是不是有点迷糊了，什么叫自定义类型，自定义类型不就是struct嘛，不是这样的哦，struct只是自定义类型里面一种比较特殊的类型而已，还有其他自定义类型申明，可以通过如下这样的申明来实现。
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```Go
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type typeName typeLiteral
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type typeName typeLiteral
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```
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请看下面这个申明自定义类型的代码
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```Go
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type ages int
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type ages int
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type money float32
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type money float32
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type months map[string]int
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type months map[string]int
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m := months {
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"January":31,
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"February":28,
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...
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"December":31,
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}
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m := months {
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"January":31,
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"February":28,
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...
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"December":31,
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}
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```
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看到了吗？简单的很吧，这样你就可以在自己的代码里面定义有意义的类型了，实际上只是一个定义了一个别名,有点类似于c中的typedef，例如上面ages替代了int
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@@ -135,79 +135,79 @@ method的语法如下：
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你可以在任何的自定义类型中定义任意多的`method`，接下来让我们看一个复杂一点的例子
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```Go
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package main
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import "fmt"
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package main
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const(
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WHITE = iota
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BLACK
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BLUE
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RED
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YELLOW
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)
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import "fmt"
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type Color byte
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const(
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WHITE = iota
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BLACK
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BLUE
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RED
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YELLOW
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)
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type Box struct {
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width, height, depth float64
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color Color
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}
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type Color byte
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type BoxList []Box //a slice of boxes
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type Box struct {
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width, height, depth float64
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color Color
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}
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func (b Box) Volume() float64 {
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return b.width * b.height * b.depth
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}
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type BoxList []Box //a slice of boxes
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func (b *Box) SetColor(c Color) {
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b.color = c
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}
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func (b Box) Volume() float64 {
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return b.width * b.height * b.depth
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}
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func (bl BoxList) BiggestColor() Color {
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v := 0.00
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k := Color(WHITE)
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for _, b := range bl {
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if bv := b.Volume(); bv > v {
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v = bv
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k = b.color
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}
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}
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return k
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}
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func (b *Box) SetColor(c Color) {
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b.color = c
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}
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func (bl BoxList) PaintItBlack() {
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for i, _ := range bl {
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bl[i].SetColor(BLACK)
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func (bl BoxList) BiggestColor() Color {
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v := 0.00
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k := Color(WHITE)
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for _, b := range bl {
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if bv := b.Volume(); bv > v {
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v = bv
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k = b.color
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}
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}
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return k
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}
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func (c Color) String() string {
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strings := []string {"WHITE", "BLACK", "BLUE", "RED", "YELLOW"}
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return strings[c]
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func (bl BoxList) PaintItBlack() {
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for i, _ := range bl {
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bl[i].SetColor(BLACK)
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}
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}
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func (c Color) String() string {
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strings := []string {"WHITE", "BLACK", "BLUE", "RED", "YELLOW"}
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return strings[c]
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}
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func main() {
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boxes := BoxList {
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Box{4, 4, 4, RED},
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Box{10, 10, 1, YELLOW},
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Box{1, 1, 20, BLACK},
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Box{10, 10, 1, BLUE},
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Box{10, 30, 1, WHITE},
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Box{20, 20, 20, YELLOW},
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}
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func main() {
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boxes := BoxList {
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Box{4, 4, 4, RED},
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Box{10, 10, 1, YELLOW},
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Box{1, 1, 20, BLACK},
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Box{10, 10, 1, BLUE},
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Box{10, 30, 1, WHITE},
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Box{20, 20, 20, YELLOW},
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}
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fmt.Printf("We have %d boxes in our set\n", len(boxes))
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fmt.Println("The volume of the first one is", boxes[0].Volume(), "cm³")
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fmt.Println("The color of the last one is",boxes[len(boxes)-1].color.String())
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fmt.Println("The biggest one is", boxes.BiggestColor().String())
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fmt.Printf("We have %d boxes in our set\n", len(boxes))
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fmt.Println("The volume of the first one is", boxes[0].Volume(), "cm³")
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fmt.Println("The color of the last one is",boxes[len(boxes)-1].color.String())
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fmt.Println("The biggest one is", boxes.BiggestColor().String())
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fmt.Println("Let's paint them all black")
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boxes.PaintItBlack()
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fmt.Println("The color of the second one is", boxes[1].color.String())
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fmt.Println("Let's paint them all black")
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boxes.PaintItBlack()
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fmt.Println("The color of the second one is", boxes[1].color.String())
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fmt.Println("Obviously, now, the biggest one is", boxes.BiggestColor().String())
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}
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fmt.Println("Obviously, now, the biggest one is", boxes.BiggestColor().String())
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}
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```
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上面的代码通过const定义了一些常量，然后定义了一些自定义类型
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@@ -252,81 +252,81 @@ method的语法如下：
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前面一章我们学习了字段的继承，那么你也会发现Go的一个神奇之处，method也是可以继承的。如果匿名字段实现了一个method，那么包含这个匿名字段的struct也能调用该method。让我们来看下面这个例子
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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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}
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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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}
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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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}
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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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}
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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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}
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//在human上面定义了一个method
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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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//在human上面定义了一个method
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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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func main() {
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mark := Student{Human{"Mark", 25, "222-222-YYYY"}, "MIT"}
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sam := Employee{Human{"Sam", 45, "111-888-XXXX"}, "Golang Inc"}
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func main() {
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mark := Student{Human{"Mark", 25, "222-222-YYYY"}, "MIT"}
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sam := Employee{Human{"Sam", 45, "111-888-XXXX"}, "Golang Inc"}
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mark.SayHi()
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sam.SayHi()
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}
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mark.SayHi()
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sam.SayHi()
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}
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```
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### method重写
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上面的例子中，如果Employee想要实现自己的SayHi,怎么办？简单，和匿名字段冲突一样的道理，我们可以在Employee上面定义一个method，重写了匿名字段的方法。请看下面的例子
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```Go
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package main
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import "fmt"
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package main
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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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import "fmt"
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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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}
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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 Employee struct {
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Human //匿名字段
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company 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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}
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//Human定义method
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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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type Employee struct {
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Human //匿名字段
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company string
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}
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//Employee的method重写Human的method
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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) //Yes you can split into 2 lines here.
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}
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//Human定义method
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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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func main() {
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mark := Student{Human{"Mark", 25, "222-222-YYYY"}, "MIT"}
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sam := Employee{Human{"Sam", 45, "111-888-XXXX"}, "Golang Inc"}
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//Employee的method重写Human的method
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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) //Yes you can split into 2 lines here.
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}
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mark.SayHi()
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sam.SayHi()
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}
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func main() {
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mark := Student{Human{"Mark", 25, "222-222-YYYY"}, "MIT"}
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sam := Employee{Human{"Sam", 45, "111-888-XXXX"}, "Golang Inc"}
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mark.SayHi()
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sam.SayHi()
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}
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```
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上面的代码设计的是如此的美妙，让人不自觉的为Go的设计惊叹！
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Reference in New Issue
Block a user