gogo-reflect

How to check if an object has a particular method?

In Go, how do you check if an object responds to a method?

For example, in Objective-C this can be achieved by doing:

if ([obj respondsToSelector:@selector(methodName:)]) { // if method exists
  [obj methodName:42]; // call the method
}
Solution

  • A simple option is to declare an interface with just the method you want to check for and then do a type assert against your type like;

     i, ok := myInstance.(InterfaceImplementingThatOneMethodIcareAbout)
 // inline iface declaration example
 i, ok = myInstance.(interface{F()})

    You likely want to use the reflect package if you plan to do anything too crazy with your type; http://golang.org/pkg/reflect

    st := reflect.TypeOf(myInstance)
m, ok := st.MethodByName("F")
if !ok {
    // method doesn't exist
} else {
    // do something like invoke m.F
}