Errors

Sun, 04 Oct 2026 00:00:00 +0000

Errors are values, not exceptions

Failure is part of the function signature and is handled right where it happens.

code, err := s.allocateCode(ctx)
if err != nil {
    return nil, fmt.Errorf("create session: %w", err)
}
return s.openSession(ctx, code)

error is just an interface:

type error interface {
    Error() string
}

Sentinel errors are package-level values callers can compare against:

var (
    ErrNotFound      = errors.New("not found")
    ErrNicknameTaken = errors.New("nickname already taken")
)

Wrap with %w to add context while keeping the original reachable: