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Getting around type incovariance in Go, a cool slice trick
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| package main | |
| import ( | |
| "fmt" | |
| "strconv" | |
| ) | |
| type Point struct { | |
| Name int | |
| Marked // You don't need to initialize it | |
| } | |
| func (p *Point) String() string { | |
| return strconv.Itoa(p.Name) | |
| } | |
| type Marker interface { | |
| Delete() | |
| Dead() bool | |
| } | |
| type Marked struct { | |
| mark bool | |
| } | |
| func (d *Marked) Delete() { | |
| d.mark = true | |
| } | |
| func (d *Marked) Dead() bool { | |
| return d.mark | |
| } | |
| // Delete removes points from slice | |
| // Previously, you had to duplicate casts up and down for each structure. | |
| func Delete[T Marker](list []T) []T { | |
| temp := list[:0] | |
| for _, item := range list { | |
| if item.Dead() { | |
| temp = append(temp, item) | |
| } | |
| } | |
| return temp | |
| } | |
| func main() { | |
| a, b, c := &Point{Name: 1}, &Point{Name: 2}, &Point{Name: 3} | |
| points := []*Point{a, b, c} | |
| fmt.Println("Before:", points) | |
| b.Delete() | |
| points = Delete(points) | |
| fmt.Println("After:", points) | |
| } |
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