| Go supports _methods_ defined on struct types. | ||
package main |
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import "fmt" |
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type rect struct { |
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width, height int |
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} |
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| This `area` method has a _receiver type_ of `*rect`. | func (r *rect) area() int { |
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return r.width * r.height |
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} |
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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 { |
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return 2*r.width + 2*r.height |
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} |
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func main() { |
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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()) |
area: 50 |
fmt.Println("perim:", r.perim()) |
perim: 30 |
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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 |
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fmt.Println("area: ", rp.area()) |
area: 50 |
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fmt.Println("perim:", rp.perim()) |
perim: 30 |
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} |