Google doesn’t have much on this topic, so here is what I found.
- You can’t use
reflect to inspect a package at runtime.
- You can use
go/parser to inspect the package if you have access to the source code
I needed to inspect a package to facilitate generating code at compile time. So
the go/parser route worked fine for me.
The following code prints out the types and consts and functions
found in the files of the ./events_pb package.
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| package main
import (
"fmt"
"go/ast"
"go/parser"
"go/token"
"os"
"path"
"strings"
)
func checkErr(err error) {
if err != nil {
fmt.Fprintf(os.Stderr, "-- %s\n", err)
os.Exit(1)
}
}
// Specify what files to parser
func onlyProtoBufFiles(info os.FileInfo) bool {
if strings.HasSuffix(info.Name(), ".pb.go") {
return true
}
return false
}
func main() {
pwd, err := os.Getwd()
checkErr(err)
dir := path.Join(pwd, "events_pb")
pkgs, err := parser.ParseDir(token.NewFileSet(), dir, onlyProtoBufFiles, 0)
if err != nil {
return
}
for _, pkg := range pkgs {
for source, f := range pkg.Files {
source = path.Base(source)
for name, object := range f.Scope.Objects {
if object.Kind == ast.Typ {
fmt.Printf("%s: Type: %s\n", source, name)
}
if object.Kind == ast.Con {
fmt.Printf("%s: Const: %s\n", source, name)
}
if object.Kind == ast.Fun {
fmt.Printf("%s: Functions: %s\n", source, name)
}
}
}
}
}
|
Output looks like this
fixtures.pb.go: Type: Bar
fixtures.pb.go: Type: Blah
fixtures.pb.go: Type: Bazz
fixtures.pb.go: Type: Foo
meta.pb.go: Const: Meta_FOO
meta.pb.go: Const: Meta_BAR
...