douchigu1723 2011-09-15 22:47
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I just saw a presentation of the Go programming language and thought I'd try to write a few lines. Everything worked fine until I tried to use an interface in this situation. How do I solve this?

package main

import "fmt"

type entity float32

func (e *entity) inc() {

type incer interface {

func doSomething(i incer) {

func main() {
    fmt.Println("Hello, 世界")

    var e entity = 3

I get the compiler error:

prog.go:24: cannot use e (type entity) as type incer in function argument:
entity does not implement incer (inc method requires pointer receiver)

I want to use a pointer so that the inc() will affect the enity outside the function. What is the syntax I should use?


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  • duanji1899 2011-09-16 00:29

    I think there is some confusion here. inc is a method of the type *entity, and not of the type entity (while you can call methods on values directly on pointers; you cannot generally call methods on pointers directly on values). What you may be confused about is why you could call, instead of having to do (&e).inc(). This is a little-known special case documented at the bottom of the Calls section in the language specification, that says if x is addressable, and &x's method set contains m, then x.m() is shorthand for (&x).m(). This applies to this case because e is a variable, so it is addressable; but other expressions may not be addressable. I would recommend that you not use this shortcut, however, as it causes confusion; it makes you think that e conforms to the interface inter, while it does not.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?



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