Make go variable accept multiple types -

i develop library in go makes use of different file formats of debug package in go standard packages (http://golang.org/pkg/debug/). idea open file , print out information file. automatically recognize correct file format testing relevant file types. instance, test if file simple mach-o or fat mach-o file, trying open file both open methods:

  file, err := macho.open(filename)   if err != nil {       fmt.println("not mach-o file.")   }   file, err = macho.openfat(filename)   if err != nil {       fmt.println("not fat mach-o file. exiting.")       return   }  

unfortunately file variable (of course) type checked, , following error:

cannot assign *macho.fatfile file (type *macho.file) in multiple assignment 

i not sure of correct way of approaching this. can point me right direction how perfom properly?

or don't declare file @ all, if you're not going it.

if _, err := macho.open(filename); err != nil {     fmt.println("not mach-o file.") } if _, err = macho.openfat(filename); err != nil {     fmt.println("not fat mach-o file. exiting.")     return }  

if wanted call function on file, declare of interface type func(s) want call, like:

var file io.closer file, err := macho.open(filename) if err != nil {     fmt.println("not mach-o file.") } file, err = macho.openfat(filename) if err != nil {     fmt.println("not fat mach-o file. exiting.")     return } file.close() 

in case it't not interesting because looks macho.file , macho.fatfile's common function close()