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https://github.com/hexops/valast
Convert Go values to their AST
https://github.com/hexops/valast
ast go go-package golang reflect repr tostring valast
Last synced: about 1 month ago
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Convert Go values to their AST
- Host: GitHub
- URL: https://github.com/hexops/valast
- Owner: hexops
- License: other
- Created: 2020-12-25T08:12:43.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2024-07-24T21:56:19.000Z (5 months ago)
- Last Synced: 2024-08-03T17:18:46.877Z (4 months ago)
- Topics: ast, go, go-package, golang, reflect, repr, tostring, valast
- Language: Go
- Homepage:
- Size: 128 KB
- Stars: 305
- Watchers: 6
- Forks: 15
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
Awesome Lists containing this project
- go-awesome - valast - outputs the `go/ast` structure of variables, similar to PHP's `var_export` function (Open source library / Debugging)
README
# valast - convert Go values to their AST 
[](https://github.com/hexops/valast/actions) [](https://codecov.io/gh/hexops/valast) [](https://goreportcard.com/report/github.com/hexops/valast)
Valast converts Go values at runtime into their `go/ast` equivalent, e.g.:
```Go
x := &foo.Bar{
a: "hello world!",
B: 1.234,
}
fmt.Println(valast.String(x))
```
Prints string:
```Go
&foo.Bar{a: "hello world!", B: 1.234}
```
## What is this useful for?
This can be useful for debugging and testing, you may think of it as a more comprehensive and configurable version of the `fmt` package's `%+v` and `%#v` formatting directives. It is similar to e.g. `repr` in Python.
## Features
- Produces Go code via a `go/ast`, defers formatting to the best-in-class Go formatter [gofumpt](https://github.com/mvdan/gofumpt).
- Fully handles unexported fields, types, and values (optional.)
- Strong emphasis on being used for producing valid Go code that can be copy & pasted directly into e.g. tests.
- [Extensively tested](https://github.com/hexops/valast/tree/main/testdata), over 88 tests and handling numerous edge cases (such as pointers to unaddressable literal values like `&"foo"` properly, and even [finding bugs in alternative packages'](https://github.com/shurcooL/go-goon/issues/15)).
## Alternatives comparison
The following are alternatives to Valast, making note of the differences we found that let us to create Valast:
- [github.com/davecgh/go-spew](https://github.com/davecgh/go-spew)
- [may be inactive](https://github.com/davecgh/go-spew/issues/128)
- Produces Go-like output, but not Go syntax.
- [github.com/shurcooL/go-goon](https://github.com/shurcooL/go-goon) (based on go-spew)
- Produces valid Go syntax, but not via a `go/ast`.
- [Produces less idiomatic/terse results](https://github.com/shurcooL/go-goon/issues/11))
- Was deprecated in favor of valast.
- [github.com/alecthomas/repr](https://github.com/alecthomas/repr)
- Produces Go syntax, but not always valid code (e.g. can emit illegal `&23`, whereas Valast will emit a valid expression `valast.Addr(23).(int)`), not via a `go/ast`.
- [Does not handle unexported fields/types/values.](https://github.com/alecthomas/repr/pull/13)
You may also wish to look at [autogold](https://github.com/hexops/autogold) and [go-cmp](https://github.com/google/go-cmp), which aim to solve the "compare Go values in a test" problem.