What is the method
In fact, as long as you understand this principle, you can basically understand the problems mentioned above.
The method is actually a special function, and the receiver is the first parameter passed in implicitly. .For example
type test struct{
name string
}
func (t test) TestValue() {
}
func (t *test) TestPointer() {
}
func main(){
t := test{}
m := test.TestValue
m(t)
m1 := (*test).TestPointer
m1(&t)
}Is it easy to understand? Now let’s add code to see the difference between pointers and non-pointers.
type test struct{
name string
}
func (t test) TestValue() {
fmt.Printf("%p\n", &t)
}
func (t *test) TestPointer() {
fmt.Printf("%p\n", t)
}
func main(){
t := test{}
//0xc42000e2c0
fmt.Printf("%p\n", &t)
//0xc42000e2e0
m := test.TestValue
m(t)
//0xc42000e2c0
m1 := (*test).TestPointer
m1(&t)
} It is estimated that some students have understood that when the actual parameter is not a pointer, the value is copied. Therefore, every time TestValue() is called, the value is copied.
If it involves the operation of modifying the value, What will be the result?type test struct{
name string
}
func (t test) TestValue() {
fmt.Printf("%s\n",t.name)
}
func (t *test) TestPointer() {
fmt.Printf("%s\n",t.name)
}
func main(){
t := test{"wang"}
//这里发生了复制,不受后面修改的影响
m := t.TestValue
t.name = "Li"
m1 := (*test).TestPointer
//Li
m1(&t)
//wang
m()
}So all students must pay attention when encountering such problems in programming.What is the relationship between these method sets? Here I borrowed from qyuhen's study in golang As for taking notes, I also recommend friends who like golang to read this book, which will be of great help in deepening their understanding of golang.
• Type T method set contains all receiver T methods.
• The type
T methods.• If type S contains anonymous field T, then S method set contains T method.
Although golang is simple and easy to use, it still has many pitfalls. The author encountered many pitfalls in the process of using golang, which will be mentioned in the blog later. Everyone is welcome. discuss together.
• If type S contains anonymous field T, then S's method set contains T T methods.
• Regardless of embedding T or
T, the set of S methods always contains T *T methods.
Conclusion