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// run -gcflags=-G=3
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"fmt"
"strconv"
)
type Setter[B any] interface {
Set(string)
type *B
}
func fromStrings1[T any, PT Setter[T]](s []string) []T {
result := make([]T, len(s))
for i, v := range s {
// The type of &result[i] is *T which is in the type list
// of Setter, so we can convert it to PT.
p := PT(&result[i])
// PT has a Set method.
p.Set(v)
}
return result
}
func fromStrings2[T any](s []string, set func(*T, string)) []T {
results := make([]T, len(s))
for i, v := range s {
set(&results[i], v)
}
return results
}
type Settable int
func (p *Settable) Set(s string) {
i, err := strconv.Atoi(s)
if err != nil {
panic(err)
}
*p = Settable(i)
}
func main() {
s := fromStrings1[Settable, *Settable]([]string{"1"})
if len(s) != 1 || s[0] != 1 {
panic(fmt.Sprintf("got %v, want %v", s, []int{1}))
}
s = fromStrings2([]string{"1"}, func(p *Settable, s string) { p.Set(s) })
if len(s) != 1 || s[0] != 1 {
panic(fmt.Sprintf("got %v, want %v", s, []int{1}))
}
}
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