71 lines
1.4 KiB
Markdown
71 lines
1.4 KiB
Markdown
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---
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title: Go Methods
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---
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## Go Methods
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Golang types can have methods. A method is a function with a special argument, the _receiver_.
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```go
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type Rectangle struct {
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height, width int64
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}
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func (r Receiver) getArea() int64 {
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return r.height * r.height
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}
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r := Rectangle{10, 20}
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r.getArea() // 200
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```
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Here, type `Rectangle` has got a method called `getArea` that returns the area of the rectangle.
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The receiver here is `r`.
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This code is equivalent to:
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```go
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type Rectangle struct {
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height, width int64
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}
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func getArea(r Receiver) int 64{
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return r.height * r.height
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}
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r := Rectangle{10, 20}
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getArea(r) // 200
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```
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Now the getArea method receives `r` as an argument, instead of a receiver. The functionality is equivalent.
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### Pointer receiver
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You can pass a pointer as a receiver:
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```go
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type MyInt int64
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func (m *MyInt) setToZero() {
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*m = MyInt(0)
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}
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m := MyInt(10)
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m.setToZero() // m == 0
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```
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### Extension methods
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If you want to create a method on a type defined in other package, e.g. `int` you can use a simple wrapper like this:
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```go
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type MyInt int64
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func (m MyInt) add10() int64 {
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return m + 10
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}
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m := MyInt(10)
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m.add10() // 20
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```
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#### More Information:
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<!-- Please add any articles you think might be helpful to read before writing the article -->
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https://tour.golang.org/methods/1
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