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https://github.com/mna/starstruct
Starlark to Go struct converter.
https://github.com/mna/starstruct
Last synced: about 2 months ago
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Starlark to Go struct converter.
- Host: GitHub
- URL: https://github.com/mna/starstruct
- Owner: mna
- License: bsd-3-clause
- Created: 2023-01-28T03:49:18.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2023-02-05T20:24:05.000Z (almost 2 years ago)
- Last Synced: 2024-10-14T08:18:16.568Z (3 months ago)
- Language: Go
- Size: 209 KB
- Stars: 3
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
Awesome Lists containing this project
- awesome-starlark - starstruct - a library for converting (Libraries and extensions)
- awesome-starlark - starstruct
README
[](https://pkg.go.dev/github.com/mna/starstruct)
[](https://github.com/mna/starstruct/actions)
# Starlark to Go struct converter
The `starstruct` package implements conversion of Go structs to [Starlark `StringDict`](https://pkg.go.dev/go.starlark.net/starlark#StringDict) and from Starlark `StringDict` to a Go struct.
It uses the `starlark` struct tag key to indicate the name of the corresponding Starlark `StringDict` key for a field and optional conversion options, as is common in Go marshalers (such as [JSON](https://pkg.go.dev/encoding/json) and [XML](https://pkg.go.dev/encoding/xml)).
Since Starlark is a useful language for configuration, and configuration can often be represented by a well-defined Go struct, the idea for this package is to make it easy to provide the default configuration (as a Go struct) to a Starlark program, and read back the final configuration after the Starlark program's execution, so that the Go code can use the Go configuration struct from there on.
The [code documentation](https://pkg.go.dev/github.com/mna/starstruct) is the canonical source for documentation.
## Installation
Note that `starstruct` requires Go 1.20+.
```
$ go get github.com/mna/starstruct
```
## Example
From `example_test.go`:
```golang
func Example() {
const script = `
def set_server(srv):
srv["ports"].append(2020)
def set_admin(adm):
adm["name"] = "root"
adm["is_admin"] = True
roles = adm["roles"]
adm["roles"] = roles.union(["editor", "admin"])
set_server(server)
set_admin(user)
`
type Server struct {
Addr string `starlark:"addr"`
Ports []int `starlark:"ports"`
}
type User struct {
Name string `starlark:"name"`
IsAdmin bool `starlark:"is_admin"`
Ignored int `starlark:"-"`
Roles []string `starlark:"roles,asset"`
}
type S struct {
Server Server `starlark:"server"`
User User `starlark:"user"`
}
// initialize with default values for the starlark script
s := S{
Server: Server{Addr: "localhost", Ports: []int{80, 443}},
User: User{Name: "Martin", Roles: []string{"viewer"}, Ignored: 42},
}
initialVars := make(starlark.StringDict)
if err := starstruct.ToStarlark(s, initialVars); err != nil {
log.Fatal(err)
}
// execute the starlark script (it doesn't create any new variables, but if
// it did, we would capture them in outputVars and merge all global vars
// together before calling FromStarlark).
var th starlark.Thread
outputVars, err := starlark.ExecFile(&th, "example", script, initialVars)
if err != nil {
log.Fatal(err)
}
allVars := mergeStringDicts(nil, initialVars, outputVars)
if err := starstruct.FromStarlark(allVars, &s); err != nil {
log.Fatal(err)
}
fmt.Printf("%v", s)
// Output:
// {{localhost [80 443 2020]} {root true 42 [viewer editor admin]}}
}
```
## License
The [BSD 3-Clause license](http://opensource.org/licenses/BSD-3-Clause).