Go function calls

[katsusan]

Go里一共有4种函数：

• top-level func
• method with value receiver
• method with pointer receiver
• func literal

调用的方式有5种：

• direct call of top-level func
• direct call of method with value receiver
• direct call of method with pointer receiver
• indirect call of func value
• indirect call of method on interface

package main


func TopLevel(x int) {}


type Pointer struct{}
func (*Pointer) M(int) {}


type Value struct{}
func (Value) M(int) {}

type Interface interface { M(int) }

var literal = func(x int) {}


func main() {

        // direct call of top-level func
        TopLevel(1)

        // direct call of method with value receiver (two spellings, but same)
        var v Value
        v.M(1)
        Value.M(v, 1)

        // direct call of method with pointer receiver (two spellings, but same)
        var p Pointer
        (&p).M(1)
        (*Pointer).M(&p, 1)
       
        // indirect call of func value (×4)
        f1 := TopLevel
        f1(1)

        f2 := Value.M
        f2(v, 1)

        f3 := (*Pointer).M
        f3(&p, 1)

        f4 := literal
        f4(1)

        // indirect call of method on interface (×3)
        var i Interface
        i = v
        i.M(1)

        i = &v
        i.M(1)

        i = &p
        i.M(1)

        Interface.M(i, 1)
        Interface.M(v, 1)
        Interface.M(&p, 1)
}

综上，总共有10种函数与调用方式的组合：

• direct call of top-level func /
• direct call of method with value receiver /
• direct call of method with pointer receiver /
• indirect call of func value / set to top-level func
• indirect call of func value / set to value method
• indirect call of func value / set to pointer method
• indirect call of func value / set to func literal
• indirect call of method on interface / containing value with value method
• indirect call of method on interface / containing pointer with value method
• indirect call of method on interface / containing pointer with pointer method

//refer: https://docs.google.com/document/d/1bMwCey-gmqZVTpRax-ESeVuZGmjwbocYs1iHplK-cjo/pub