BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Who is willing to comment (ValueTye and Mediator) Goto page 1, 2  Next          BorlandTalk.com Forum Index -> Delphi OO design View previous topic :: View next topic   Author Message Bart Guest Posted: Tue Dec 06, 2005 11:20 pm    Post subject: Who is willing to comment (ValueTye and Mediator) Hi All, After a lot of googling and reading Joanna's, Iman, and Lee's source code I have finally (at least I hope) found a solution for my problems. Now I hope if someone willing to look at my code and comment. I have posted in the attachment group: TVMediator.zip Hope to hear, Bart Back to top Lee_Nover Guest Posted: Wed Dec 07, 2005 1:03 am    Post subject: Re: Who is willing to comment (ValueTye and Mediator) Quote: Now I hope if someone willing to look at my code and comment. separate Observer and Subject ideally each class/interface should be in it's own unit (unless they're tightly coupled like _lists of_ some type) if you do it the way I do then RegisterAttributes should be called from TProperties class (also naming the classes more appropriately wouldn't hurt) again I'd use a hashed list .. you can use (drop/replace) THashedStringList from IniFiles unit (I'll replace it with a TStringHash soon - enormous speed boost ! talking about 100x gain) instead of returning a pointer in RegisterAttribute you should return a class .. TValueType in this case (I'll check why I return a pointer :/) why does TValueType have two value fields ? fAsBoolean and fAsInteger ? (each ValueType entity should represent only one Value) create a TBoolean and a TInteger class instead I'm not using mediators coz I'm keeping the framework as lightweight as possible .. but your code looks ok :) Back to top Bart Guest Posted: Wed Dec 07, 2005 10:59 am    Post subject: Re: Who is willing to comment (ValueTye and Mediator) Thanks Lee, you really helped me a lot. Back to top Bart Guest Posted: Wed Dec 07, 2005 11:04 am    Post subject: Re: Who is willing to comment (ValueTye and Mediator) Thanks Lee, you really helped me a lot. Back to top Marcos Guest Posted: Wed Dec 07, 2005 1:35 pm    Post subject: Re: Who is willing to comment (ValueTye and Mediator) See the post "OPF Questions" above. I talk about infra framework it have ValueTypeFramework ready! Back to top Joanna Carter [TeamB] Guest Posted: Wed Dec 07, 2005 1:48 pm    Post subject: Re: Who is willing to comment (ValueTye and Mediator) "Bart" <@> a écrit dans le message de news: 43961c73$1 (AT) newsgroups (DOT) borland.com... Quote: Now I hope if someone willing to look at my code and comment. I have posted in the attachment group: TVMediator.zip Sorry to say, but you are mixing all sorts of different techniques and coming up with a bit of a mess :-( I will try to answer more fully when I get back home on Friday, but in the meanwhile : Contrary to Lee, I would say that keeping two related classes like TObserver and TSubject in the same unit is fine. Do not use things like AsInteger and AsBoolean in the same Value Type, there is absolutely no need for this and it will get even more confusing when you get to the stage of adding CustomerValueType, OrderValueType, etc... Take heart though, we all started somewhere and those of us who made the most mistakes (and corrected them) ended up with the most competent frameworks. :-) Joanna -- Joanna Carter [TeamB] Consultant Software Engineer Back to top Bart Guest Posted: Wed Dec 07, 2005 2:33 pm    Post subject: Re: Who is willing to comment (ValueTye and Mediator) Hi Joanna, Thanks for responding: Quote: Contrary to Lee, I would say that keeping two related classes like TObserver and TSubject in the same unit is fine. I did some cleanup and I have seperated them in two units which I think is also fine. Quote: Do not use things like AsInteger and AsBoolean in the same Value Type, there is absolutely no need for this and it will get even more confusing when you get to the stage of adding CustomerValueType, OrderValueType, etc... I have created a class for several valuetypes. They do now have a value property. As Lee propossed. Quote: Take heart though, we all started somewhere and those of us who made the most mistakes (and corrected them) ended up with the most competent frameworks. Please feel free to comment as much as you like. I am so glad that there are people willing to do because at my company I am the only Delphi programmer so I cannot discuss my ideas. I just hope that I will come to a clean and good OO design. I have posted the latest version to the attachment group: VTMediator2.zip Hope to hear, Thanks a lot, Bart Back to top Iman L Crawford Guest Posted: Wed Dec 07, 2005 3:45 pm    Post subject: Re: Who is willing to comment (ValueTye and Mediator) "Bart" <-> wrote in news:4396f275$1 (AT) newsgroups (DOT) borland.com: Quote: I have posted the latest version to the attachment group: VTMediator2.zip My only question is why you have your ValueTypes derive from TSubject and your ControlMediator derive from TObject. What if you want your ValueType to be an observer? Usually you would want want to use composition or aggregation. (I think those are the correct terms) -- Iman Back to top Lee_Nover Guest Posted: Wed Dec 07, 2005 4:00 pm    Post subject: Re: Who is willing to comment (ValueTye and Mediator) Quote: Sorry to say, but you are mixing all sorts of different techniques andcoming up with a bit of a mess agreed :) Quote: Contrary to Lee, I would say that keeping two related classes like TObserver and TSubject in the same unit is fine. nothing wrong having a pattern defined and implemented in one class it's just that I prefer implementations in separate units :) Back to top Bart Guest Posted: Wed Dec 07, 2005 4:03 pm    Post subject: Re: Who is willing to comment (ValueTye and Mediator) Hi Iman, Quote: My only question is why you have your ValueTypes derive from TSubject and your ControlMediator derive from TObject. My model holds the ValueType objects. These objects are the subjects that are observered by the mediatiors. I am not quite sure which version of my source you have but my ControlMediator derives from TObserver. Quote: What if you want your ValueType to be an observer? What should it observe ? Quote: Usually you would want want to use composition or aggregation. (I think those are the correct terms) Maybe that is also a possiblity but I think (still learning here) inheritance is ok here. Bart Back to top Lee_Nover Guest Posted: Wed Dec 07, 2005 4:10 pm    Post subject: Re: Who is willing to comment (ValueTye and Mediator) Quote: What if you want your ValueType to be an observer? What should it observe ? it's attributes check my code again and you'll see (Tdpo2Object) Quote: Usually you would want want to use composition or aggregation. (I think those are the correct terms) Maybe that is also a possiblity but I think (still learning here) inheritance is ok here. since you're using strictly objects then you can't implement both Observer and Subject thru inheritance either use composition or use interfaces Back to top Iman L Crawford Guest Posted: Wed Dec 07, 2005 4:32 pm    Post subject: Re: Who is willing to comment (ValueTye and Mediator) "Bart" <-> wrote in news:4397079d (AT) newsgroups (DOT) borland.com: Quote: My model holds the ValueType objects. These objects are the subjects that are observered by the mediatiors. I try to have my classes do just one thing. Even when using interfaces, I would have another class implement the needed functionality. This is just my opinion, I'm not a expert by any definition. Quote: I am not quite sure which version of my source you have but my ControlMediator derives from TObserver. I should have typed TObserver. Quote: What should it observe ? Other classes or valuetypes. Quote: Maybe that is also a possiblity but I think (still learning here) inheritance is ok here. I'm still learning too. All my suggestions are just that, suggestions. -- Iman Back to top Bart Guest Posted: Wed Dec 07, 2005 5:33 pm    Post subject: Re: Who is willing to comment (ValueTye and Mediator) Quote: What if you want your ValueType to be an observer? What should it observe ? it's attributes check my code again and you'll see (Tdpo2Object) I find it rather convenient that my ValueType object is the subject. In this way I can easy attach my mediator as an observer which on his turn can update my view. I am trying to implement a MGM here. Maybe I am understanding it wrong but why should a ValueType object observe an attribute of an model which holds the list with Valuetype objects himself ? Quote: since you're using strictly objects then you can't implement both Observer and Subject thru inheritance either use composition or use interfaces I do understand this Bart Bart Back to top Lee_Nover Guest Posted: Wed Dec 07, 2005 8:36 pm    Post subject: Re: Who is willing to comment (ValueTye and Mediator) Quote: I find it rather convenient that my ValueType object is the subject I have it like that too in your example TProperties would want to observer it's asstributes so you'd add a field FObserver: TObserver to your TProperties class and attach an it in the RegisterAttribute method Procedure TProperties.RegisterAttribute(const aAttribute: TvalueType; const Name: String); begin assert(Name <> '', 'Attribute name cannot be empty'); fAttributes.AddObject(Name, aAttribute); aAttribute.Attach(fObserver); end; you'd create the observer in the constructor and do some wiring like fObserver.OnUpdate := HandleObserverUpdate; Back to top Bart Guest Posted: Thu Dec 08, 2005 8:43 am    Post subject: Re: Who is willing to comment (ValueTye and Mediator) Quote: I have it like that too in your example TProperties would want to observer it's asstributes And this is the point that I don't understand. It is probably my lag of experience. What is the use ? Can you try to explain it ot me ? 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