how to set and get fields in Golang structs?

问题:

After creating a struct like this:

type Foo struct {
   name string        

}
func (f Foo) SetName(name string){
    f.name=name
}

func (f Foo) GetName string (){
   return f.name
}

How do I create a new instance of Foo and set and get the name? I tried the following:

p:=new(Foo)
p.SetName("Abc")
name:=p.GetName()
fmt.Println(name)

Nothing gets printed, because name is empty. So how do I set and get a field inside a struct?

回答1:

Commentary (and working) example:

package main

import "fmt"

type Foo struct {
    name string
}

// SetName receives a pointer to Foo so it can modify it.
func (f *Foo) SetName(name string) {
    f.name = name
}

// Name receives a copy of Foo since it doesn't need to modify it.
func (f Foo) Name() string {
    return f.name
}

func main() {
    // Notice the Foo{}. The new(Foo) was just a syntactic sugar for &Foo{}
    // and we don't need a pointer to the Foo, so I replaced it.
    // Not relevant to the problem, though.
    p := Foo{}
    p.SetName("Abc")
    name := p.Name()
    fmt.Println(name)
}

Test it and take A Tour of Go to learn more about methods and pointers, and the basics of Go at all.

回答2:

Setters and getters are not that idiomatic to Go. Especially the getter for a field x is not named GetX but just X. See http://golang.org/doc/effective_go.html#Getters

If the setter does not provide special logic, e.g. validation logic, there is nothing wrong with exporting the field and neither providing a setter nor a getter method. (This just feels wrong for someone with a Java background. But it is not.)

回答3:

For example,

package main

import "fmt"

type Foo struct {
    name string
}

func (f *Foo) SetName(name string) {
    f.name = name
}

func (f *Foo) Name() string {
    return f.name
}

func main() {
    p := new(Foo)
    p.SetName("Abc")
    name := p.Name()
    fmt.Println(name)
}

Output:

Abc