Alternatively, if you are walking an AST and only interested in the exported names then you can use https://golang.org/pkg/go/ast/#PackageExports . It will filter your tree to only elements that are exported before you begin traversal.
As to your specific case of determining if a type used in a method signature is exported, I'd ask: Does it matter if the source package is the same one where the method is defined or is it any non-builtin, exported types used in the signature? I believe the case of "exported name used in a method within the same package" can be determined by iterating of the 'Params.List' attribute of the ast.FuncType and looking for elements of the slice that are of type '*ast.Ident' and checking the corresponding 'IsExported' method call results. For complete coverage, you'd also need to check for *ast.ArrayType, *ast.ChanType, *ast.MapType, *ast.Ellipsis (for uses of the type as a variadic), *ast.FuncType (and its corresponding arguments and return types), and *ast.StarExpr (for uses of the type as a pointer). The case of "any non-builtin, exported type from any package" would use the previous logic but also add in checking for elements of 'Params.List' that are of type '*ast.SelectorExpr'. While I'm sure there is a case where this is not true, the elements of type *ast.SelectorExpr in the parameter list of an *ast.FuncType are usually references to a type exported by another package (think "http.Handler"). The 'X' attribute can be converted to *ast.Ident for the source package name and the 'Sel' attribute contains the name of the referenced type. Note that the package name might actually be a local alias when the file imports with ' import myname "net/http" '. https://play.golang.org/p/yNKAQe_YSV PS the implementation of 'IsExported' used by everything checks the capitalisation of the first letter to make its choice: https://golang.org/src/go/ast/ast.go?s=16357:16390#L516 On Mon, Apr 24, 2017 at 2:49 AM Tejas Manohar <m...@tejas.io> wrote: > Agreed! I ended up casting to types.NamedType (or pointer then elem())... > I'll try your method too! > On Sun, Apr 23, 2017 at 11:11 PM Axel Wagner < > axel.wagner...@googlemail.com> wrote: > >> I'd say, probably type-asserting to a *types.TypeName >> <https://golang.org/pkg/go/types/#TypeName> and then use Exported() >> <https://golang.org/pkg/go/types/#TypeName.Exported> (the code of which >> also leads to ast.IsExported <https://golang.org/pkg/go/ast/#IsExported> >> ). >> >> Side-note: You probably shouldn't rely on parsing the output of String() >> of any value, just as you shouldn't rely on parsing the output of >> error.Error(). >> >> On Mon, Apr 24, 2017 at 7:06 AM, <m...@tejas.io> wrote: >> >>> https://golang.org/pkg/go/types/#Type >>> >>> Is there a helper function to determine whether a *types.Type* is >>> exported? It seems like I can do some string parsing like >>> >>> t := something.Type() >>> parts := strings.Split(t.String(), ".") // go/ast.Node => ["go/ast", >>> "Node"] >>> ident := parts[len(parts)-1] // "Node" >>> exported := strings.IsUpper(ident[0]) >>> >>> but I imagine there's a simpler, more robust way. The end goal is to >>> find out whether a type of a method argument is exported-- e.g. >>> namedType := obj.Type().(*types.Named) >>> method := namedType.Method(0) >>> signature := method.Type().(*types.Signature) >>> signature.Params().At(0).Type() // is this exported? >>> >>> And, for some context, all of this is from walking go/ast >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "golang-nuts" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to golang-nuts+unsubscr...@googlegroups.com. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- > > Best regards, > > Tejas Manohar > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
