参数和接收器有什么区别

问题描述：

I am following a Go tutorial and am stuck as I cant understand a particular method signature:

func (p *Page) save() error {
    filename := p.Title + ".txt"
    return ioutil.WriteFile(filename, p.Body, 0600)
}

The docs explain this as follows:

This method's signature reads: "This is a method named save that takes as its receiver p, a pointer to Page . It takes no parameters, and returns a value of type error."

I cant understand what the receiver is. I would read this as it being a parameter but then I would expect a parameter to be in save().

我正在关注Go教程，由于无法理解特定的方法签名而被困住： p>

  func（p * Page）save（）错误{
 filename：= p.Title +“ .txt” 
 return ioutil.WriteFile（filename，p.Body，0600）
}  
  code>  pre> 
 
 文档对此进行了如下解释： p> 
 
 
 
 此方法的签名为：“这是一个方法 命名为save的接收者p是指向Page的指针。它不带参数，并且返回错误类型的值。“  p> 
  blockquote> 
 
 
我不明白 接收者是。 我将其作为参数读取，但随后我希望参数位于 save（） code>中。 p> 
  div>

答

The receiver is the object on what you declare your method.

When want to add a method to an object, you use this syntax.

ex: http://play.golang.org/p/5n-N_Ov6Xz

答

The receiver is just a special case of a parameter. Go provides syntactic sugar to attach methods to types by declaring the first parameter as a receiver.

For instance:

func (p *Page) save() error

reads "attach a method called save that returns an error to the type *Page", as opposed to declaring:

func save(p *Page) error

that would read "declare a function called save that takes one parameter of type *Page and returns an error"

As proof that it's only syntactic sugar you can try out the following code:

p := new(Page)
p.save()
(*Page).save(p)

Both last lines represent exactly the same method call.

Also, read this answer.

参数和接收器有什么区别

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