This problem is found in the watch go when the Context of the source code, is simply to structure A embedded interface I, then constructs A embedded structure B, B instantiate structure and returning A pointer to A instance, can be directly converted into interface in type I, so do it himself A small test, the specific code is as follows, what is this principle, it's better if have relevant memory model shows that,

 
Package the main 

The import "FMT" 

Var CTX TestInt 

//TestInt is an interface 
Type TestInt interface {
Func1 () 
Func2 () 
Func3 - a non-class function () 
} 

Func (* emptyCtx) func1 () {
FMT. Println (" func1 ") 
} 

Func (* emptyCtx) func2 () {
FMT. Println (" func2 ") 
} 

Func (* emptyCtx) func3 - a non-class function () {
FMT. Println (" func3 - a non-class function ") 
} 

Type emptyCtx int 

Var (
Background=new (emptyCtx) 
) 

//Background is a function 
Func Background () TestInt {
Return background 
} 

//Struct1 is a struct 
Type Struct1 struct {
TestInt 
Str1 string 
} 

//Struct2 is a struct 
Type Struct2 struct {
Struct1 
Str2 string 
} 

Func newStruct1 (parent TestInt) Struct1 {
Return Struct1 {
TestInt: parent, 
Str1: "test1", 
} 
} 

//NewStruct2 is a function 
Func NewStruct2 (parent TestInt) TestInt {

Return & amp; Struct2 {
: Struct1 newStruct1 (parent), 
Str2: "test2", 
} 
} 

Func main () {

CTX:=Background () 
CTX=NewStruct2 (CTX) 

CTX. Func1 () 
CTX. Func2 () 
CTX. Func3 - a non-class function () 
} 

CodePudding user response:

Feel nothing to illustrate, with easy to understand:
Is the interface, B has A, that natural B has A interface
Is just like A is the wiring board, B is house, house has A patch panel. A, B that why B can't use A patch panel?

Interface is a standard
A consistent with the interface specification, then A is the interface of A type
B in line with the interface specification, that B is a type of the interface

TestInt equivalent to formulate A patch panel interface specification (what rule can provide A wiring board, what to provide, such as regulation interface has three slot)
EmptyCtx is according to TestInt standard led to A wiring board, there are three slots
Type Struct1 struct {
TestInt//the wall has a TestInt interface specification (has installed slot)
Str1 string
}

Type Struct2 struct {
Struct1//it has interface with conforming to the guidelines of TestInt wall
Str2 string
}

CTX:=Background ()//produce A wiring board
CTX=NewStruct2 (CTX)//install the wiring board installed in the house of A slot in the

CTX. Func1 ()//house can use strips A slot 1
CTX. Func2 ()//house can use strips A slot 2
CTX. Func3 - A non-class function ()//house can use strips A slot 3

No inheritance in go, only combination
Inheritance is is a relationship, that is, inheritance and parent the same type, the parent class or interface subclass has
Combination is from a relationship, that is, combination with members of the type, some members of the interface combination with