Blog / Standard Library

The Attr type

July 2, 2026

Other than logger methods, the slog.Attr type is probably the thing you’ll use the most in your use of the slog package:

Types

type Attr

type Attr struct {
	Key   string
	Value Value
}

An Attr is a key-value pair.

This type has several type-specific constructors, too, but we’re going to do an abbrevaited look at them, because they’re highly repetitive.

func Any

func Any(key string, value any) Attr

Any returns an Attr for the supplied value. See AnyValue for how values are treated.

Any provides the general-purpose way to create an Attr for any type.

var foo struct  {
  Some   int
  Random string
  Fields float64
}

slog.Any("foo", foo{})
slog.Any("bool", true) // Functionally equivalent to using slog.Bool

Notably, slog.Any can be used for types that also have their own constructors, listed below. The only difference in using the type-specific constructors is that they don’t have to do any runtime type assertion.

func Bool

func Duration

func Float64

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