codekingpro/portable-devtools

1// run2 3// Copyright 2021 The Go Authors. All rights reserved.4// Use of this source code is governed by a BSD-style5// license that can be found in the LICENSE file.6 7// Test method calls on type parameters8 9package main10 11import (12	"fmt"13	"reflect"14	"strconv"15)16 17// Simple constraint18type Stringer interface {19	String() string20}21 22func stringify[T Stringer](s []T) (ret []string) {23	for _, v := range s {24		ret = append(ret, v.String())25	}26	return ret27}28 29type myint int30 31func (i myint) String() string {32	return strconv.Itoa(int(i))33}34 35// Constraint with an embedded interface, but still only requires String()36type Stringer2 interface {37	CanBeStringer2() int38	SubStringer239}40 41type SubStringer2 interface {42	CanBeSubStringer2() int43	String() string44}45 46func stringify2[T Stringer2](s []T) (ret []string) {47	for _, v := range s {48		ret = append(ret, v.String())49	}50	return ret51}52 53func (myint) CanBeStringer2() int {54	return 055}56 57func (myint) CanBeSubStringer2() int {58	return 059}60 61// Test use of method values that are not called62func stringify3[T Stringer](s []T) (ret []string) {63	for _, v := range s {64		f := v.String65		ret = append(ret, f())66	}67	return ret68}69 70func main() {71	x := []myint{myint(1), myint(2), myint(3)}72 73	got := stringify(x)74	want := []string{"1", "2", "3"}75	if !reflect.DeepEqual(got, want) {76		panic(fmt.Sprintf("got %s, want %s", got, want))77	}78 79	got = stringify2(x)80	if !reflect.DeepEqual(got, want) {81		panic(fmt.Sprintf("got %s, want %s", got, want))82	}83 84	got = stringify3(x)85	if !reflect.DeepEqual(got, want) {86		panic(fmt.Sprintf("got %s, want %s", got, want))87	}88}89