Aaron, Functionally, there really is no difference between using the object factory the way we did and instantiating an object in the application scope as you are suggesting.
When a variable, or object, is passed 'by reference', it simply means that a new instance of the variable or object is not created, however a 'pointer' is used to 'point' to the original variable. Here is a basic code snippet that might help clarify. <cfset var1 = structNew() /> <cfset var1.myName = 'Scott' /> <cfset var2 = var1 /> <cfset var2.myName = 'Aaron' /> <cfoutput>#var1.myName#</cfoutput> This code will output 'Aaron'. The reason is that var2 does not actually contain a structure, rather just a 'pointer' to var1. In the objectFactory we used, when an object was 'registered' it was put into a structure. When we call the create() method on the objectFactory it checks to see if the object is supposed to be a singleton and if it is already stored in the structure. If it is, it merely returns a pointer to the object. As I said, while the code looks as if we are actually creating a new object on each page where a gateway is needed, it is only created if it doesn't exist or if you manually reinit the application. In a future presentation we will cover design patterns. In some design patterns it would be more advantageous to use a factory like we did as opposed to instantiating an object in the application scope. Hope this helps. On 11/21/06, Aaron Roberson <[EMAIL PROTECTED]> wrote: > > I had a hard time understanding passing by reference and by value in > my Java class... I did download the code from Phill's blog and I > couldn't figure out why you guys kept using the create method of the > objectFactory on each page... now I get it. > > However, in this thread I am asking a much more basic question. Why > not just create the objects in Application.cfm and ditch the whole > objectFactory thing? It seems like it would be a whole lot easier to > just instantiate a gateway object in Application.cfm then it is to > register and then create each object using the objectFactory. > > What am I missing? There always seems to be a good reason to make > things harder when using OOP, so there has to be something too it, > right? > > Thanks, > Aaron > > On 11/21/06, Scott Stroz <[EMAIL PROTECTED]> wrote: > > Aaron, > > > > Thanx for watching the presentation. I hope it helped you. > > > > The first part of the presentation was to demonstrate some OO > principals, > > and to show how you could transform a procedural application into one > more > > OO. It was during this part where we were creating all the gateway > objects > > when we needed them. In the latter portion of the presentation, we > > discussed optimizing the application with the use of factories and > caching > > objects in a shared scope (the application scope). > > > > If you go to Phill's site, > > > http://www.phillnacelli.net/blog/index.cfm/2006/11/17/Central-PA-CFUG-Preso-Recapand > > download the code, you will see that we used an object factory to > > create > > the gateway objects using the create() method. When these gateways were > > used in the application, they are not being created, merely returned > from > > the object factory. Since the gateway objects were specified as a > > 'singleton', only one instance of the objects will ever be in > memory. In > > the application files, when we once again called the create() method of > the > > object factory, it merely returned a reference to the object already > cached > > in the application scope (Remember, complex data types, including > objects, > > are passed by reference). > > > > So while the code on the some of the files may seem like new objects are > > being created each time a page is hit, a look at the code in > application.cfm, > > and in objectFactory.cfc will show that the only time a new gateway > object > > is created is when one does not already exist, or if you manually reinit > the > > applciation by adding ?reinit=true to the end of a URL. > > > > On 11/21/06, Aaron Roberson <[EMAIL PROTECTED]> wrote: > > > > > > I watched a presentation from the guys at AboutWeb.com about Object > > > Oriented Programming in Coldfusion and Phill Nacelli's Object Factory > > > got me wondering a few things. > > > > > > Is it possible to initialize all of the object gateways into the > > > application scope in Application.cfm? It seems like it would be better > > > to create and initialize the object once and then reference it on each > > > page instead of creating it on each page. > > > > > > In Application.cfm I would have: > > > > > > <cfset application.personGateway = > > > createObject("component","path.personGateway").init(application.dsn) > > > /> > > > > > > Then on the pages I would just do something like: > > > > > > <cfset getPeople = application.personGateway /> > > > > > > What do you think, am I off somewhere with all of this OOP stuff? > > > > > > -Aaron > > > > > > > > > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Introducing the Fusion Authority Quarterly Update. 80 pages of hard-hitting, up-to-date ColdFusion information by your peers, delivered to your door four times a year. http://www.fusionauthority.com/quarterly Archive: http://www.houseoffusion.com/groups/CF-Talk/message.cfm/messageid:261386 Subscription: http://www.houseoffusion.com/groups/CF-Talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4
