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https://github.com/fatih/errwrap
Go tool to wrap and fix errors with the new %w verb directive
https://github.com/fatih/errwrap
analyzer errwrap go golang tools
Last synced: 4 days ago
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Go tool to wrap and fix errors with the new %w verb directive
- Host: GitHub
- URL: https://github.com/fatih/errwrap
- Owner: fatih
- License: other
- Created: 2019-11-30T18:48:29.000Z (about 5 years ago)
- Default Branch: main
- Last Pushed: 2024-06-20T07:15:50.000Z (6 months ago)
- Last Synced: 2024-12-01T01:03:09.496Z (11 days ago)
- Topics: analyzer, errwrap, go, golang, tools
- Language: Go
- Homepage: https://arslan.io
- Size: 36.1 KB
- Stars: 372
- Watchers: 6
- Forks: 16
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- go-awesome - errwrap - Go tool for wrapping and debugging with new `%w` verb directive (Open source library / Error Handling)
- awesome-golang-repositories - errwrap
README
# errwrap [](https://github.com/fatih/errwrap/actions)
Wrap and fix Go errors with the new **`%w`** verb directive. This tool analyzes
`fmt.Errorf()` calls and reports calls that contain a verb directive that is
different than the new `%w` verb directive [introduced in Go v1.13](https://golang.org/doc/go1.13#error_wrapping). It's also capable of rewriting calls to use the new `%w` wrap verb directive.
## Install
```bash
# minimum v1.16 is required
go install github.com/fatih/errwrap@latest
```
or download one of the [pre-compiled binaries from the releases page](https://github.com/fatih/errwrap/releases/latest) and copy to the desired location.
## Usage
By default, `errwrap` prints the output of the analyzer to stdout. You can pass
a file, directory or a Go package:
```sh
$ errwrap foo.go # pass a file
$ errwrap ./... # recursively analyze all files
$ errwrap github.com/fatih/gomodifytags # or pass a package
```
When called it displays the error with the line and column:
```
[email protected]/main.go:200:16: call could wrap the error with error-wrapping directive %w
[email protected]/main.go:641:17: call could wrap the error with error-wrapping directive %w
[email protected]/main.go:749:15: call could wrap the error with error-wrapping directive %w
```
`errwrap` is also able to rewrite your source code to replace any verb
directive used for an `error` type with the `%w` verb directive. Assume we have
the following source code:
```
$ cat demo.go
package main
import (
"errors"
"fmt"
)
func main() {
_ = foo()
}
func foo() error {
err := errors.New("bar!")
return fmt.Errorf("foo failed: %s: %s bar ...", "foo", err)
}
```
Calling `errwrap` with the `-fix` flag will rewrite the source code:
```
$ errwrap -fix main.go
main.go:14:9: call could wrap the error with error-wrapping directive %w
```
```diff
diff --git a/main.go b/main.go
index 41d1c42..6cb42b8 100644
--- a/main.go
+++ b/main.go
@@ -11,5 +11,5 @@ func main() {
func foo() error {
err := errors.New("bar!")
- return fmt.Errorf("failed for %s with error: %s", "foo", err)
+ return fmt.Errorf("failed for %s with error: %w", "foo", err)
}
```
## Whether to Wrap or not?
Wrapping an error is not always the best approach. Wrapping exposes the
underlying error and makes it part of your public API. This means clients who
rely on them could see breaking changes if you change your underlying
implementation or don't wrap anymore.
The blog post **[Working with Errors in Go
1.13](https://blog.golang.org/go1.13-errors)** contains a section called
`Whether to Wrap` that explains this in more detail
## Credits
This tool is built on top of the excellent `go/analysis` package that makes it
easy to write custom analyzers in Go. If you're interested in writing a tool,
check out my **[Using go/analysis to write a custom
linter](https://arslan.io/2019/06/13/using-go-analysis-to-write-a-custom-linter/)**
blog post.
Also part of the code that parses the verb directives is from the
`go/analysis/passes/printf` analyzer. It's a simplified version and might
contain discrepancies.