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go/test/typeparam/stringable.go
Matthew Dempsky 5355753009 [dev.typeparams] test/typeparam: gofmt -w
We don't usually reformat the test directory, but all of the files in
test/typeparam are syntactically valid. I suspect the misformattings
here are because developers aren't re-installing gofmt with
-tags=typeparams, not intentionally exercising non-standard
formatting.

Change-Id: I3767d480434c19225568f3c7d656dc8589197183
Reviewed-on: https://go-review.googlesource.com/c/go/+/338093
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
2021-07-28 21:40:40 +00:00

47 lines
847 B
Go

// 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"
"strings"
)
type Stringer interface {
String() string
}
// StringableList is a slice of some type, where the type
// must have a String method.
type StringableList[T Stringer] []T
func (s StringableList[T]) String() string {
var sb strings.Builder
for i, v := range s {
if i > 0 {
sb.WriteString(", ")
}
sb.WriteString(v.String())
}
return sb.String()
}
type myint int
func (a myint) String() string {
return strconv.Itoa(int(a))
}
func main() {
v := StringableList[myint]{myint(1), myint(2)}
if got, want := v.String(), "1, 2"; got != want {
panic(fmt.Sprintf("got %s, want %s", got, want))
}
}