Hi, In your *second* example, making Output() a method of Animal will work, since it uses only the members (fields) of Animal, and not the fields of specific animals (or any behavior that varies between animals). That's why I'm insisting on *real* and *specific* examples, not synthetic ones.
/npat On Wednesday, November 23, 2016 at 6:08:00 AM UTC+2, Tong Sun wrote: > > No Nick, making Output() a member method won't work. > See my OP and Jesse's answer. I.e., I have to change it from a member > function to a pure function. > > On Tue, Nov 22, 2016 at 6:25 PM, Nick Patavalis <nick.pa...@gmail.com > <javascript:>> wrote: > >> Hi, >> >> There is no direct mapping of what you can do with virtual functions in >> other OO languages, and Go. There are different compromises you have to >> make; because of this, synthetic examples will probably not help much. >> >> That being said, in the case of your last example I would make Output() a >> method of Animal. >> The Speak() methods of the specific animals would then call Output(). >> >> /npat >> >> On Wednesday, November 23, 2016 at 12:03:54 AM UTC+2, Tong Sun wrote: >>> >>> >>> >>> On Tue, Nov 22, 2016 at 4:29 PM, Jesse McNelis wrote: >>> >>>> On Wed, Nov 23, 2016 at 8:16 AM, Tong Sun wrote: >>>> > Hi, >>>> > >>>> > How to architect the OO's virtual function in Go? >>>> > >>>> > Please take a look at this (not working) Go program >>>> > https://play.golang.org/p/qrBX6ScABp >>>> > >>>> > Please think of the "func Output()" as a very complicated function >>>> that I >>>> > only want to define once at the base level, not to duplicate into >>>> each sub >>>> > classes. >>>> > >>>> > How can I make it works so that the last output statement, instead of >>>> being, >>>> > >>>> > fmt.Printf("[%v] %s: [%0.2f]\n", k, v.Name(), v.Area()) >>>> > >>>> > >>>> > will be this instead: >>>> > >>>> > fmt.Printf("[%v] %s\n", k, v.Output()) >>>> > >>>> >>>> You define a function: >>>> >>>> func Output(s Shape) string { >>>> return s.Name() + "'s area size is " + s.Area() >>>> } >>>> >>>> Go uses interfaces for polymorphism. >>>> Other OOP languages can use inheritance for polymorphism too, but Go >>>> doesn't have inheritance. >>>> >>> >>> Thanks Jesse. That works. >>> >>> However I just realized that it is only part of my problem. >>> >>> I have a huge list of common variables that I defined in my "base >>> class", changing it from a member function to a pure function causes almost >>> every single variable now undefined. >>> >>> I can demonstrate the problem with this code >>> https://play.golang.org/p/QjCtD9rGpa >>> >>> So, once again, thinking in OO, I'll define all of the common variables >>> in base class, and common functionalities in virtual functions. How to make >>> that idea work in Go? >>> >>> For the above specific code, how to easily make "func Output" works? >>> >>> Thanks >>> >>> -- >> You received this message because you are subscribed to a topic in the >> Google Groups "golang-nuts" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/golang-nuts/f_62HEOIBV4/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> golang-nuts...@googlegroups.com <javascript:>. >> 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.
