Let's see: CFCs have given us a "this" scope which is *public*; instance variables can't be made private except by the kludge of using an unnamed scope. We have CFCs presented as OO, but which has no concept of super. We have no overloading of methods in CFCs.
Were I given to irony, I might say that "I am not anti-CFC per se, but it does tend to live in its own little bubble and it takes words, concepts and phrases from the much larger world of OO and misuses them in a way that causes confusion." ;-) Hal Helms Preorder "Discovering ColdFusion Components (CFCs)" at www.techspedition.com -----Original Message----- From: Sean A Corfield [mailto:[EMAIL PROTECTED]] Sent: Sunday, September 01, 2002 12:27 PM To: CF-Talk Subject: Re: CFC theory On Sunday, September 1, 2002, at 08:27 , Jeffry Houser wrote: > I almost skipped over this post because it was all quotes. ( I > imagine that was because the list was bouncing stuff for a bit). Yeah, sorry about that. > 3. Is the data created inside a component protected from outside > forces? I'm a little grey on this one. You can create component > specific variables using the this scope. "this" scope is public, the unnamed scope is private so this gets a YES. > 2. Do CFCs support Overloading / Overriding? Not in related objects. Overloading no, overriding yes. (And I don't really agree that overloading is actually *necessary* to claim 'OO-ness' - much of the worst code I have seen in OO languages is because of overloading and there are almost always ways around it). > A child CFC inherits all parent > methods as is. You do not have the ability to change functionality of > inherited methods. Yes you do. Try the following: // base.cfc: <cfcomponent> <cffunction name="foo" returntype="string"> <cfreturn "I'm base.foo"/> </cffunction> </cfcomponent> // derived.cfc: <cfcomponent extends="base"> <cffunction name="foo" returntype="string"> <cfreturn "I'm derived.foo"/> </cffunction> </cfcomponent> // test.cfm: <cfset b = createObject("component","base")/> <cfset d = createObject("component","derived")/> <cfoutput> b.foo() is #b.foo()#<br> d.foo() is #d.foo()#<br> </cfoutput> You can pass d to anything expecting a base component instance so substitutability is preserved and polymorphism is also preserved. > 3. Do CFCs support inheritance? Yes, they do. However without the > overloading / overriding it is nothing more than a fancy include. Overloading is mostly irrelevant for inheritance - in most (all?) OO languages, when you inherit an overloaded set of methods, you have to reimplement all of them in order to preserve overloading - overloading normally only occurs within each class definition. As pointed out above, CFMX does have overriding so inheritance *is* more than a fancy include. > 4. Do CFCs support polymorphism? I would say no. I cannot create two > different methods with the same exact name, but different argument > types. That is the essence of polymorphism. No, that is overloading. Polymorphism requires overriding - see above - so CFMX *does* support polymorphism. Polymorphism is 'virtual functions' in most every OO language, something that CFMX does have. > For me, the lack of the ability to overload is what makes me say you > cannot apply Object Oriented development As I say above, overloading really has nothing to do with OO. C has overloading (Oh, yes, it does! Check out the latest ISO C standard to see how they worked that in. Not for all types, admittedly, but they did add it). (Do I need to mention that I wrote the first ANSI-validated C compiler, spent eight years on the ISO C++ Standards Committee - three as secretary - designing parts of that language and also worked on the UK and ISO Java Study Groups for a couple of years as well? :) Sean A Corfield -- http://www.corfield.org/blog/ "If you're not annoying somebody, you're not really alive." -- Margaret Atwood ______________________________________________________________________ This list and all House of Fusion resources hosted by CFHosting.com. The place for dependable ColdFusion Hosting. FAQ: http://www.thenetprofits.co.uk/coldfusion/faq Archives: http://www.mail-archive.com/cf-talk@houseoffusion.com/ Unsubscribe: http://www.houseoffusion.com/index.cfm?sidebar=lists
