xerrors.Formatter
// A Formatter formats error messages.
type Formatter interface {
// FormatError prints the receiver's first error and returns the next error in
// the error chain, if any.
FormatError(p Printer) (next error)
}
xerrors.Printer
// A Printer formats error messages.
//
// The most common implementation of Printer is the one provided by package fmt
// during Printf (as of Go 1.13). Localization packages such as golang.org/x/text/message
// typically provide their own implementations.
type Printer interface {
// Print appends args to the message output.
Print(args ...interface{})
// Printf writes a formatted string.
Printf(format string, args ...interface{})
// Detail reports whether error detail is requested.
// After the first call to Detail, all text written to the Printer
// is formatted as additional detail, or ignored when
// detail has not been requested.
// If Detail returns false, the caller can avoid printing the detail at all.
Detail() bool
}
xerrors.Wrapper
// A Wrapper provides context around another error.
type Wrapper interface {
// Unwrap returns the next error in the error chain.
// If there is no next error, Unwrap returns nil.
Unwrap() error
}
xerrors.As
// As finds the first error in err's chain that matches the type to which target
// points, and if so, sets the target to its value and returns true. An error
// matches a type if it is assignable to the target type, or if it has a method
// As(interface{}) bool such that As(target) returns true. As will panic if target
// is not a non-nil pointer to a type which implements error or is of interface type.
//
// The As method should set the target to its value and return true if err
// matches the type to which target points.
//
// Deprecated: As of Go 1.13, use errors.As instead.
func As(err error, target interface{}) bool
xerrors.Caller
// Caller returns a Frame that describes a frame on the caller's stack.
// The argument skip is the number of frames to skip over.
// Caller(0) returns the frame for the caller of Caller.
func Caller(skip int) Frame
xerrors.Errorf
// Errorf formats according to a format specifier and returns the string as a
// value that satisfies error.
//
// The returned error includes the file and line number of the caller when
// formatted with additional detail enabled. If the last argument is an error
// the returned error's Format method will return it if the format string ends
// with ": %s", ": %v", or ": %w". If the last argument is an error and the
// format string ends with ": %w", the returned error implements an Unwrap
// method returning it.
//
// If the format specifier includes a %w verb with an error operand in a
// position other than at the end, the returned error will still implement an
// Unwrap method returning the operand, but the error's Format method will not
// return the wrapped error.
//
// It is invalid to include more than one %w verb or to supply it with an
// operand that does not implement the error interface. The %w verb is otherwise
// a synonym for %v.
//
// Note that as of Go 1.13, the fmt.Errorf function will do error formatting,
// but it will not capture a stack backtrace.
func Errorf(format string, a ...interface{}) error
xerrors.FormatError
// FormatError calls the FormatError method of f with an errors.Printer
// configured according to s and verb, and writes the result to s.
func FormatError(f Formatter, s fmt.State, verb rune)
xerrors.Is
// Is reports whether any error in err's chain matches target.
//
// An error is considered to match a target if it is equal to that target or if
// it implements a method Is(error) bool such that Is(target) returns true.
//
// Deprecated: As of Go 1.13, use errors.Is instead.
func Is(err error, target error) bool
xerrors.New
// New returns an error that formats as the given text.
//
// The returned error contains a Frame set to the caller's location and
// implements Formatter to show this information when printed with details.
func New(text string) error
xerrors.Opaque
// Opaque returns an error with the same error formatting as err
// but that does not match err and cannot be unwrapped.
func Opaque(err error) error
xerrors.Unwrap
// Unwrap returns the result of calling the Unwrap method on err, if err implements
// Unwrap. Otherwise, Unwrap returns nil.
//
// Deprecated: As of Go 1.13, use errors.Unwrap instead.
func Unwrap(err error) error