mirror of
https://github.com/pkg/errors.git
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3cdd33210d
* Introduce Stacktrace and Frame This PR is a continuation of a series aimed at exposing the stack trace information embedded in each error value. The secondary effect is to deprecated the `Fprintf` helper. Taking cues from from @chrishines' `stack` package this PR introduces a new interface `Stacktrace() []Frame` and a `Frame` type, similar in function to the `runtime.Frame` type (although lacking its iterator type). Each `Frame` implemnts `fmt.Formatter` allowing it to print itself. The older `Location` interface is still supported but also deprecated.
88 lines
1.7 KiB
Go
88 lines
1.7 KiB
Go
package errors_test
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import (
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"fmt"
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"os"
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"github.com/pkg/errors"
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)
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func ExampleNew() {
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err := errors.New("whoops")
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fmt.Println(err)
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// Output: whoops
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}
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func ExampleNew_fprint() {
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err := errors.New("whoops")
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errors.Fprint(os.Stdout, err)
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// Output: github.com/pkg/errors/example_test.go:18: whoops
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}
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func ExampleWrap() {
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cause := errors.New("whoops")
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err := errors.Wrap(cause, "oh noes")
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fmt.Println(err)
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// Output: oh noes: whoops
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}
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func fn() error {
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e1 := errors.New("error")
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e2 := errors.Wrap(e1, "inner")
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e3 := errors.Wrap(e2, "middle")
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return errors.Wrap(e3, "outer")
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}
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func ExampleCause() {
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err := fn()
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fmt.Println(err)
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fmt.Println(errors.Cause(err))
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// Output: outer: middle: inner: error
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// error
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}
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func ExampleFprint() {
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err := fn()
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errors.Fprint(os.Stdout, err)
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// Output: github.com/pkg/errors/example_test.go:36: outer
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// github.com/pkg/errors/example_test.go:35: middle
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// github.com/pkg/errors/example_test.go:34: inner
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// github.com/pkg/errors/example_test.go:33: error
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}
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func ExampleWrapf() {
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cause := errors.New("whoops")
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err := errors.Wrapf(cause, "oh noes #%d", 2)
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fmt.Println(err)
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// Output: oh noes #2: whoops
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}
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func ExampleErrorf() {
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err := errors.Errorf("whoops: %s", "foo")
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errors.Fprint(os.Stdout, err)
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// Output: github.com/pkg/errors/example_test.go:67: whoops: foo
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}
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func ExampleError_Stacktrace() {
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type Stacktrace interface {
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Stacktrace() []errors.Frame
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}
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err, ok := errors.Cause(fn()).(Stacktrace)
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if !ok {
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panic("oops, err does not implement Stacktrace")
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}
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st := err.Stacktrace()
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fmt.Printf("%+v", st[0:2]) // top two framces
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// Output: [github.com/pkg/errors/example_test.go:33 github.com/pkg/errors/example_test.go:78]
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}
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