mirror of
https://github.com/golang/go
synced 2024-11-19 05:24:42 -07:00
57 lines
930 B
Go
57 lines
930 B
Go
|
// run
|
||
|
|
|
||
|
|
// Copyright 2022 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"
|
||
|
|
|
||
|
|
type I interface {
|
||
|
|
M()
|
||
|
|
}
|
||
|
|
|
||
|
|
type S struct {
|
||
|
|
str string
|
||
|
|
}
|
||
|
|
|
||
|
|
func (s *S) M() {}
|
||
|
|
|
||
|
|
var _ I = &S{}
|
||
|
|
|
||
|
|
type CloningMap[K comparable, V any] struct {
|
||
|
|
inner map[K]V
|
||
|
|
}
|
||
|
|
|
||
|
|
func (cm CloningMap[K, V]) With(key K, value V) CloningMap[K, V] {
|
||
|
|
result := CloneBad(cm.inner)
|
||
|
|
result[key] = value
|
||
|
|
return CloningMap[K, V]{result}
|
||
|
|
}
|
||
|
|
|
||
|
|
func CloneBad[M ~map[K]V, K comparable, V any](m M) M {
|
||
|
|
r := make(M, len(m))
|
||
|
|
for k, v := range m {
|
||
|
|
r[k] = v
|
||
|
|
}
|
||
|
|
return r
|
||
|
|
}
|
||
|
|
|
||
|
|
func main() {
|
||
|
|
s1 := &S{"one"}
|
||
|
|
s2 := &S{"two"}
|
||
|
|
|
||
|
|
m := CloningMap[string, I]{inner: make(map[string]I)}
|
||
|
|
m = m.With("a", s1)
|
||
|
|
m = m.With("b", s2)
|
||
|
|
|
||
|
|
it, found := m.inner["a"]
|
||
|
|
if !found {
|
||
|
|
panic("a not found")
|
||
|
|
}
|
||
|
|
if _, ok := it.(*S); !ok {
|
||
|
|
panic(fmt.Sprintf("got %T want *main.S", it))
|
||
|
|
}
|
||
|
|
}
|