mirror of
https://github.com/golang/go
synced 2024-11-24 09:30:07 -07:00
b8248fab89
This is a feature that is not understood well enough and may have subtle repercussions impacting future changes. Disable for Go 1.18. The actual change is trivial: disable a branch through a flag. The remaining changes are adjustments to tests. Fixes #51576. Change-Id: Ib77b038b846711a808315a8889b3904e72367bce Reviewed-on: https://go-review.googlesource.com/c/go/+/391135 Trust: Robert Griesemer <gri@golang.org> Run-TryBot: Robert Griesemer <gri@golang.org> Reviewed-by: Robert Findley <rfindley@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
76 lines
1.6 KiB
Go
76 lines
1.6 KiB
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"
|
|
)
|
|
|
|
// Numeric expresses a type constraint satisfied by any numeric type.
|
|
type Numeric interface {
|
|
~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 |
|
|
~int | ~int8 | ~int16 | ~int32 | ~int64 |
|
|
~float32 | ~float64 |
|
|
~complex64 | ~complex128
|
|
}
|
|
|
|
// Sum returns the sum of the provided arguments.
|
|
func Sum[T Numeric](args ...T) T {
|
|
var sum T
|
|
for i := 0; i < len(args); i++ {
|
|
sum += args[i]
|
|
}
|
|
return sum
|
|
}
|
|
|
|
// Ledger is an identifiable, financial record.
|
|
type Ledger[T ~string, K Numeric] struct {
|
|
// ID identifies the ledger.
|
|
ID_ T
|
|
|
|
// Amounts is a list of monies associated with this ledger.
|
|
Amounts_ []K
|
|
|
|
// SumFn is a function that can be used to sum the amounts
|
|
// in this ledger.
|
|
SumFn_ func(...K) K
|
|
}
|
|
|
|
// Field accesses through type parameters are disabled
|
|
// until we have a more thorough understanding of the
|
|
// implications on the spec. See issue #51576.
|
|
// Use accessor methods instead.
|
|
|
|
func (l Ledger[T, _]) ID() T { return l.ID_ }
|
|
func (l Ledger[_, K]) Amounts() []K { return l.Amounts_ }
|
|
func (l Ledger[_, K]) SumFn() func(...K) K { return l.SumFn_ }
|
|
|
|
func PrintLedger[
|
|
T ~string,
|
|
K Numeric,
|
|
L interface {
|
|
~struct {
|
|
ID_ T
|
|
Amounts_ []K
|
|
SumFn_ func(...K) K
|
|
}
|
|
ID() T
|
|
Amounts() []K
|
|
SumFn() func(...K) K
|
|
},
|
|
](l L) {
|
|
fmt.Printf("%s has a sum of %v\n", l.ID(), l.SumFn()(l.Amounts()...))
|
|
}
|
|
|
|
func main() {
|
|
PrintLedger(Ledger[string, int]{
|
|
ID_: "fake",
|
|
Amounts_: []int{1, 2, 3},
|
|
SumFn_: Sum[int],
|
|
})
|
|
}
|