Yes... so every specific animal type implements it's own Output() method, which does the trivial IsA() part, and calls Animal's Output() for the common complicated parts...
On Nov 23, 2016 16:35, "Tong Sun" <suntong...@gmail.com> wrote: > Have you noticed the IsA() func call there? > > On Wed, Nov 23, 2016 at 4:05 AM, Nick Patavalis <nick.patava...@gmail.com> > wrote: > >> 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> >>> 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/to >>>> pic/golang-nuts/f_62HEOIBV4/unsubscribe. >>>> To unsubscribe from this group and all its topics, send an email to >>>> golang-nuts...@googlegroups.com. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >> 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/to >> pic/golang-nuts/f_62HEOIBV4/unsubscribe. >> To unsubscribe from this group and all its topics, 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.
