Your own methods can be added to any class. Just ensure they are introduced as class extensions attached to your project's package. Use the checkbox at the bottom of the system browser. > On 13 Sep 2020, at 16:44, Roelof Wobben via Pharo-users <pharo-users@lists.pharo.org> wrote: > > > > > -------- Doorgestuurd bericht -------- > Onderwerp: Re: [Pharo-users] How can I make this more OOP > Datum: Sun, 13 Sep 2020 16:43:59 +0200 > Van: Roelof Wobben <r.wobben@home.nl> <mailto:r.wobben@home.nl> > Aan: Noury Bouraqadi <bouraqadi@gmail.com> <mailto:bouraqadi@gmail.com> > > Hello, Noury, > > Thanks for letting me see this but I wonder if it is good practice to place my own methods on the Object and UndefinedObject ? > > Roelof > > > Op 13-9-2020 om 14:51 schreef Noury Bouraqadi: >> Hi Roelof, >> >> Polymorphism is the answer. >> >> Object >> flattenInto: result >> result nextPut: anObject >> >> UndefinedObject >> flattenInto: result >> ^self >> >> Collection >> flattenInto: result >> self do: [ :item | item flattenInto: result ] >> >> flatten: anObject >> ^ (OrderedCollection streamContents: [ :stream | anObject flattenInto: stream ]) asArray >> >> Noury >> >> >