mirror of
https://github.com/Luzifer/nginx-sso.git
synced 2024-12-21 05:11:17 +00:00
81 lines
2.5 KiB
Go
81 lines
2.5 KiB
Go
// Copyright 2013, 2014 Canonical Ltd.
|
|
// Licensed under the LGPLv3, see LICENCE file for details.
|
|
|
|
/*
|
|
[godoc-link-here]
|
|
|
|
The juju/errors provides an easy way to annotate errors without losing the
|
|
orginal error context.
|
|
|
|
The exported `New` and `Errorf` functions are designed to replace the
|
|
`errors.New` and `fmt.Errorf` functions respectively. The same underlying
|
|
error is there, but the package also records the location at which the error
|
|
was created.
|
|
|
|
A primary use case for this library is to add extra context any time an
|
|
error is returned from a function.
|
|
|
|
if err := SomeFunc(); err != nil {
|
|
return err
|
|
}
|
|
|
|
This instead becomes:
|
|
|
|
if err := SomeFunc(); err != nil {
|
|
return errors.Trace(err)
|
|
}
|
|
|
|
which just records the file and line number of the Trace call, or
|
|
|
|
if err := SomeFunc(); err != nil {
|
|
return errors.Annotate(err, "more context")
|
|
}
|
|
|
|
which also adds an annotation to the error.
|
|
|
|
When you want to check to see if an error is of a particular type, a helper
|
|
function is normally exported by the package that returned the error, like the
|
|
`os` package does. The underlying cause of the error is available using the
|
|
`Cause` function.
|
|
|
|
os.IsNotExist(errors.Cause(err))
|
|
|
|
The result of the `Error()` call on an annotated error is the annotations joined
|
|
with colons, then the result of the `Error()` method for the underlying error
|
|
that was the cause.
|
|
|
|
err := errors.Errorf("original")
|
|
err = errors.Annotatef(err, "context")
|
|
err = errors.Annotatef(err, "more context")
|
|
err.Error() -> "more context: context: original"
|
|
|
|
Obviously recording the file, line and functions is not very useful if you
|
|
cannot get them back out again.
|
|
|
|
errors.ErrorStack(err)
|
|
|
|
will return something like:
|
|
|
|
first error
|
|
github.com/juju/errors/annotation_test.go:193:
|
|
github.com/juju/errors/annotation_test.go:194: annotation
|
|
github.com/juju/errors/annotation_test.go:195:
|
|
github.com/juju/errors/annotation_test.go:196: more context
|
|
github.com/juju/errors/annotation_test.go:197:
|
|
|
|
The first error was generated by an external system, so there was no location
|
|
associated. The second, fourth, and last lines were generated with Trace calls,
|
|
and the other two through Annotate.
|
|
|
|
Sometimes when responding to an error you want to return a more specific error
|
|
for the situation.
|
|
|
|
if err := FindField(field); err != nil {
|
|
return errors.Wrap(err, errors.NotFoundf(field))
|
|
}
|
|
|
|
This returns an error where the complete error stack is still available, and
|
|
`errors.Cause()` will return the `NotFound` error.
|
|
|
|
*/
|
|
package errors
|