英文:
Instantiate a package variable using just the name
问题
我正在尝试为一个包中的一些导出类型添加一些简单的验证代码，该包中充满了常量。我想遍历这个包，找出导出的常量（它们只是字符串），并验证它们的格式。
可以将其想象成我有一个名为flags的包，导出了常量FlagDoAThing = "do-a-thing"。我想遍历该包并查看这些值是什么。
举个例子，我有两个文件：
// main.go
func main() {
cfg := &packages.Config{
Mode: packages.NeedTypes,
}
pkgs, _ := packages.Load(cfg, "package-inspector/other")
pkg := pkgs[0]
scope := pkg.Types.Scope()
for _, name := range scope.Names() {
fmt.Println(name)
obj := scope.Lookup(name)
fmt.Println(obj)
fmt.Println("\t", obj.Id(), obj.Type())
}
}
然后在我的其他包中：
package other
const (
ExportedOne = "exported_one"
ExportedTwo = "exported_two"
privateOne = "private_one"
)
在本地运行时（无法在 playground 中运行），我看到的输出是：
go run main.go
ExportedOne
const package-inspector/other.ExportedOne untyped string
ExportedOne untyped string
ExportedTwo
const package-inspector/other.ExportedTwo untyped string
ExportedTwo untyped string
我想要做的是获取ExportedOne的值。
英文:
I am trying to add some simple validation code for some exported types in a package full of constants. I want to walk the package, figure out the exported consts (which are just strings) and verify their format.
Think of it like I have a flags package that exports consts FlagDoAThing = "do-a-thing". I want to walk that package and check out what those values are.
As an example I've got two files:
// main.go
func main() {
cfg := &packages.Config{
Mode: packages.NeedTypes,
}
pkgs, _ := packages.Load(cfg, "package-inspector/other")
pkg := pkgs[0]
scope := pkg.Types.Scope()
for _, name := range scope.Names() {
fmt.Println(name)
obj := scope.Lookup(name)
fmt.Println(obj)
fmt.Println("\t", obj.Id(), obj.Type())
}
}
Then in my other package I have
package other
const (
ExportedOne = "exported_one"
ExportedTwo = "exported_two"
privateOne = "private_one"
)
When running locally (couldn't get the playground to like me) I am seeing
go run main.go
ExportedOne
const package-inspector/other.ExportedOne untyped string
ExportedOne untyped string
ExportedTwo
const package-inspector/other.ExportedTwo untyped string
ExportedTwo untyped string
What I'm trying to do is get a handle on the value of ExportedOne.
答案1
得分: 1
你可以对对象进行类型断言，将其断言为*types.Const，然后通过其Val方法访问该值。
o := s.Lookup(name)
if c, ok := o.(*types.Const); ok {
fmt.Println(c.Val())
}
示例见：https://go.dev/play/p/oXX7Mo897bk
英文:
You can type-assert the object to *types.Const and then access the value through its Val method.
o := s.Lookup(name)
if c, ok := o.(*types.Const); ok {
fmt.Println(c.Val())
}
See example: https://go.dev/play/p/oXX7Mo897bk
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