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// 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 slog
import (
// An Attr is a key-value pair.
type Attr struct {
Key string
Value Value
// String returns an Attr for a string value.
func String(key, value string) Attr {
return Attr{key, StringValue(value)}
// Int64 returns an Attr for an int64.
func Int64(key string, value int64) Attr {
return Attr{key, Int64Value(value)}
// Int converts an int to an int64 and returns
// an Attr with that value.
func Int(key string, value int) Attr {
return Int64(key, int64(value))
// Uint64 returns an Attr for a uint64.
func Uint64(key string, v uint64) Attr {
return Attr{key, Uint64Value(v)}
// Float64 returns an Attr for a floating-point number.
func Float64(key string, v float64) Attr {
return Attr{key, Float64Value(v)}
// Bool returns an Attr for a bool.
func Bool(key string, v bool) Attr {
return Attr{key, BoolValue(v)}
// Time returns an Attr for a time.Time.
// It discards the monotonic portion.
func Time(key string, v time.Time) Attr {
return Attr{key, TimeValue(v)}
// Duration returns an Attr for a time.Duration.
func Duration(key string, v time.Duration) Attr {
return Attr{key, DurationValue(v)}
// Group returns an Attr for a Group Value.
// The first argument is the key; the remaining arguments
// are converted to Attrs as in [Logger.Log].
// Use Group to collect several key-value pairs under a single
// key on a log line, or as the result of LogValue
// in order to log a single value as multiple Attrs.
func Group(key string, args ...any) Attr {
return Attr{key, GroupValue(argsToAttrSlice(args)...)}
func argsToAttrSlice(args []any) []Attr {
var (
attr Attr
attrs []Attr
for len(args) > 0 {
attr, args = argsToAttr(args)
attrs = append(attrs, attr)
return attrs
// Any returns an Attr for the supplied value.
// See [Value.AnyValue] for how values are treated.
func Any(key string, value any) Attr {
return Attr{key, AnyValue(value)}
// Equal reports whether a and b have equal keys and values.
func (a Attr) Equal(b Attr) bool {
return a.Key == b.Key && a.Value.Equal(b.Value)
func (a Attr) String() string {
return fmt.Sprintf("%s=%s", a.Key, a.Value)
// isEmpty reports whether a has an empty key and a nil value.
// That can be written as Attr{} or Any("", nil).
func (a Attr) isEmpty() bool {
return a.Key == "" && a.Value.num == 0 && a.Value.any == nil