Go by Example: Methods
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Go supports methods defined on struct types. |
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package main
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import "fmt"
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type rect struct {
width, height int
}
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This |
func (r *rect) area() int {
return r.width * r.height
}
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Methods can be defined for either pointer or value receiver types. Here’s an example of a value receiver. |
func (r rect) perim() int {
return 2*r.width + 2*r.height
}
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func main() {
r := rect{width: 10, height: 5}
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Here we call the 2 methods defined for our struct. |
fmt.Println("area: ", r.area())
fmt.Println("perim:", r.perim())
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Go automatically handles conversion between values and pointers for method calls. You may want to use a pointer receiver type to avoid copying on method calls or to allow the method to mutate the receiving struct. |
rp := &r
fmt.Println("area: ", rp.area())
fmt.Println("perim:", rp.perim())
}
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$ go run methods.go
area: 50
perim: 30
area: 50
perim: 30
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Next we’ll look at Go’s mechanism for grouping and naming related sets of methods: interfaces. |
Next example: Interfaces.