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7bb721b938
The old os references are still valid, but update our code to reflect best practices and get used to the new locations. Code compiled with the bootstrap toolchain (cmd/asm, cmd/dist, cmd/compile, debug/elf) must remain Go 1.4-compatible and is excluded. For #41190. Change-Id: I8f9526977867c10a221e2f392f78d7dec073f1bd Reviewed-on: https://go-review.googlesource.com/c/go/+/243907 Trust: Russ Cox <rsc@golang.org> Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Rob Pike <r@golang.org>
70 lines
2.0 KiB
Go
70 lines
2.0 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package errors implements functions to manipulate errors.
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//
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// The New function creates errors whose only content is a text message.
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//
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// The Unwrap, Is and As functions work on errors that may wrap other errors.
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// An error wraps another error if its type has the method
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//
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// Unwrap() error
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//
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// If e.Unwrap() returns a non-nil error w, then we say that e wraps w.
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//
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// Unwrap unpacks wrapped errors. If its argument's type has an
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// Unwrap method, it calls the method once. Otherwise, it returns nil.
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//
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// A simple way to create wrapped errors is to call fmt.Errorf and apply the %w verb
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// to the error argument:
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//
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// errors.Unwrap(fmt.Errorf("... %w ...", ..., err, ...))
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//
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// returns err.
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//
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// Is unwraps its first argument sequentially looking for an error that matches the
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// second. It reports whether it finds a match. It should be used in preference to
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// simple equality checks:
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//
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// if errors.Is(err, fs.ErrExist)
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//
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// is preferable to
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//
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// if err == fs.ErrExist
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//
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// because the former will succeed if err wraps fs.ErrExist.
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//
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// As unwraps its first argument sequentially looking for an error that can be
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// assigned to its second argument, which must be a pointer. If it succeeds, it
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// performs the assignment and returns true. Otherwise, it returns false. The form
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//
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// var perr *fs.PathError
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// if errors.As(err, &perr) {
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// fmt.Println(perr.Path)
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// }
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//
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// is preferable to
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//
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// if perr, ok := err.(*fs.PathError); ok {
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// fmt.Println(perr.Path)
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// }
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//
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// because the former will succeed if err wraps an *fs.PathError.
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package errors
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// New returns an error that formats as the given text.
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// Each call to New returns a distinct error value even if the text is identical.
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func New(text string) error {
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return &errorString{text}
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}
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// errorString is a trivial implementation of error.
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type errorString struct {
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s string
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}
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func (e *errorString) Error() string {
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return e.s
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}
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