libgo/go/gob/error.go

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package gob
   6
   7 import (
   8         "fmt"
   9         "os"
  10 )
  11
  12 // Errors in decoding and encoding are handled using panic and recover.
  13 // Panics caused by user error (that is, everything except run-time panics
  14 // such as "index out of bounds" errors) do not leave the file that caused
  15 // them, but are instead turned into plain os.Error returns.  Encoding and
  16 // decoding functions and methods that do not return an os.Error either use
  17 // panic to report an error or are guaranteed error-free.
  18
  19 // A gobError wraps an os.Error and is used to distinguish errors (panics) generated in this package.
  20 type gobError struct {
  21         os.Error
  22 }
  23
  24 // errorf is like error but takes Printf-style arguments to construct an os.Error.
  25 func errorf(format string, args ...interface{}) {
  26         error(fmt.Errorf(format, args...))
  27 }
  28
  29 // error wraps the argument error and uses it as the argument to panic.
  30 func error(err os.Error) {
  31         panic(gobError{Error: err})
  32 }
  33
  34 // catchError is meant to be used as a deferred function to turn a panic(gobError) into a
  35 // plain os.Error.  It overwrites the error return of the function that deferred its call.
  36 func catchError(err *os.Error) {
  37         if e := recover(); e != nil {
  38                 *err = e.(gobError).Error // Will re-panic if not one of our errors, such as a runtime error.
  39         }
  40         return
  41 }