Jim, The problem you're running into is why we so urgently need for CF to have the concept of "null" - a symbol that fulfills the contract for any class. Without that, you're going to have to find some kludge to prevent against run-time errors if you have a returntype attribute enabled. As for the right kludge, I don't think it much matters which one you choose.
Hal Helms See halhelms.com for classes in... Java for ColdFusion Programmers Fusebox 4 Mach-II OO Applications with CFCs -----Original Message----- From: Jim Davis [mailto:[EMAIL PROTECTED] Sent: Friday, September 19, 2003 4:43 PM To: CF-Talk Subject: Yet another OO/CFC question This one's probably simple but my brain doesn't want to handle it. I've got a "Venue" CFC that contains information about performance/exhibit areas. Some venues feature many rooms or areas. For example Boston Common has the Frog Pond, the Brewer's Fountain, and the Bandstand; the Boston Ballet building has 5 studios; etc The net result is that each venue may have a single parent and may have many children. I'm an old hand at using "parent"/"child" processing in SQL but am unclear how to model this in a CFC. My first assumption was that the Venue component would have a "Parent" property of type "Venue". My problem occurs when a venue doesn't have a component. When I'm writing my "getter" I'm not sure how to handle the returntype. Most simple types are defaulted to the empty string - what of How would this normally be done? Would you: 1) Populate the "Parent" property with a Venue object if needed, but leave it as the empty string if not? And then use something like "NOT IsSimpleValue()" to determine if it's populated? 2) Populate the "Parent" property with a Venue object if needed, but leave it UNDEFINED if not. 3) Create another property as a "gatekeeper" for this one; something like "isChild" populated with a Boolean value? 4) Always populate the property using either a real parent or a self-reference (in effect saying "when I'm my own dad, we're at the top")? 5) Populate the property with an "empty venue" (one that's instantiated but not populated)? 6) Something else entirely? My goal, of course, is to access the object as seamlessly as possible (having external object do a lot of "checking" on the return doesn't seem very clean). I guess, to make it simple, I'm asking how to best deal with optional custom datatypes. Thanks in advance. Jim Davis ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Message: http://www.houseoffusion.com/lists.cfm?link=i:4:137780 Archives: http://www.houseoffusion.com/lists.cfm?link=t:4 Subscription: http://www.houseoffusion.com/lists.cfm?link=s:4 Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4 Signup for the Fusion Authority news alert and keep up with the latest news in ColdFusion and related topics. http://www.fusionauthority.com/signup.cfm
