On 7/10/07, Andrew Scott <[EMAIL PROTECTED]> wrote: > Sean why are you so against this? I welcome this with great open arms...
Java needed interfaces because it is a statically typed language and had chosen not to support multiple inheritance. It had no choice. In ColdFusion, all type checking is done at run time. So if you use interfaces, you will get a *runtime* check, just like all the other checks. And if you screw up, you'll get a runtime error. If you use interfaces, the error just has different text in it (OK, that's a *slight* oversimplification :) Furthermore, since CF is a dynamic language, you can change methods on an object after constructing it, thus removing any guarantees that an interface would buy you. You remove a method or simply replace a method with a different signature. The interface no longer applies. Then there's the actual details of how cfinterface performs its type check. It requires that the function signatures match exactly, as do the return types. That's not how interfaces work in statically typed languages. An interface defines a constraining API, not an exact API: you can specify arguments (in an implementation class method) that are compatible with the interface method arguments (e.g., adding optional arguments or using more permissive types). You can also specify more constrained return types since those can't violate the interface (i.e., an implementation method can return a subtype of the interface method's return type). Finally (thank god you say!), other dynamic OO languages don't have interfaces - and don't need them. The only reason CF8 has interfaces is to satisfy the CF-should-be-more-like-Java crowd. And, yes, I admit I was the person who entered the original ER to add interfaces and, yes, I whipped up support from the community. I regret that. I should have left well alone. I've probably done more to cause the CF-should-be-more-like-Java argument than anyone and that was a big mistake on my part. I've seen the light now... I hope others do too... -- Sean A Corfield -- (904) 302-SEAN An Architect's View -- http://corfield.org/ "If you're not annoying somebody, you're not really alive." -- Margaret Atwood ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| ColdFusion 8 beta â Build next generation applications today. Free beta download on Labs http://www.adobe.com/cfusion/entitlement/index.cfm?e=labs_adobecf8_beta Archive: http://www.houseoffusion.com/groups/CF-Talk/message.cfm/messageid:283363 Subscription: http://www.houseoffusion.com/groups/CF-Talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=11502.10531.4
