Question about Discovering CFCs
Hey Everyone, I just purchased Discovering CFCs by Hal Helms and I already know that the book is somewhat out of date (Hal told me so). However, what I really wanted was an introduction to OO and CFCs and this seemed like a descent starting point. I am starting to get further into the book (on page 50 right now) and I'm starting to see more CFC code. What I wanted to find out is what stuff is out of date, if it's possible to generalize. Are there any sites out there that outline the changes since MX? Any suggestions would be much appreciated! Thanks, Mike ~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;207172674;29440083;f Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:319026 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=11502.10531.4
Re: Question about Discovering CFCs
Most of the general ideas are still applicable. The biggest differences that I can think of are: - All function-local variables must be declared with the var keyword - The VARIABLES scope within a CFC represents private data - The VARIABLES scope should be used instead of the THIS scope for object properties to enforce encapsulation - An init() method is the de-facto constructor method - We can now call super.[method] to invoke methods on a superclass. If you can keep those rules in your head as you read (which I realize may be difficult), the majority of the concepts are still valid (composition, polymorphism, etc,). (Yes, I know the variables scope behaves like protected, not private. Yes, I know some people prefer keeping properties in the THIS scope. I kept the list simple because it's already going to be hard enough for him to keep track of it and there's no need to dive into minutiae at this point.) Regards, Brian On Sat, Feb 7, 2009 at 8:06 PM, Mike Soultanian msoul...@csulb.edu wrote: Hey Everyone, I just purchased Discovering CFCs by Hal Helms and I already know that the book is somewhat out of date (Hal told me so). However, what I really wanted was an introduction to OO and CFCs and this seemed like a descent starting point. I am starting to get further into the book (on page 50 right now) and I'm starting to see more CFC code. What I wanted to find out is what stuff is out of date, if it's possible to generalize. Are there any sites out there that outline the changes since MX? Any suggestions would be much appreciated! Thanks, Mike ~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;207172674;29440083;f Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:319027 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4
Re: Question about Discovering CFCs
Brian Kotek wrote: - All function-local variables must be declared with the var keyword Yeah, I've read extensively that it's very important to do this with every variable declared inside a function. Btw, does this also mean that query names need to be var-scoped as well? i.e. cfset var GetParks = 1 cfquery name=GetParks datasource=dsn SELECT name FROM table /cfquery - The VARIABLES scope within a CFC represents private data That I understand. - The VARIABLES scope should be used instead of the THIS scope for object properties to enforce encapsulation Yeah, I noticed that the book uses the this scope. I also noticed that the book outputs data from CFCs which I've read is a nono in regards to best practices. I'm assuming the correct method to retrieve the data stored in the properties is by calling the class' methods, correct? - An init() method is the de-facto constructor method Correct me if I'm wrong, but based on my initial reading of CFCs on the web, it seems like there are three ways of setting up constructor data: putting any cf tags or functions in the constructor area, putting a cfset init() statement in the constructor area that calls the init() method, or calling the init() method during the object instantiation. Is there a preferred method? Maybe I'm not understanding the goal of the init() method and to whom that data is supposed to be made available. Is it for the purpose of providing data to the newly created object or is it to initialize data for the other methods in the class.. or both? If anyone has any pages describing constructors and their uses (even if it's in another language), that would be helpful. - We can now call super.[method] to invoke methods on a superclass. seems simple enough. Don't have any near-future plans to call super methods just yet until I get my head wrapped around this :) If you can keep those rules in your head as you read (which I realize may be difficult), the majority of the concepts are still valid (composition, polymorphism, etc,). I think knowing about the this scope best practices is helpful. Was the variables and var scope not available at the time (Yes, I know the variables scope behaves like protected, not private. Yes, I know some people prefer keeping properties in the THIS scope. I kept the list simple because it's already going to be hard enough for him to keep track of it and there's no need to dive into minutiae at this point.) I like the idea of keeping the properties local to the CFC otherwise you break the benefits of encapsulation (or at least, I see it as a benefit). What's the difference between private and protected? thanks! Mike Regards, Brian On Sat, Feb 7, 2009 at 8:06 PM, Mike Soultanian msoul...@csulb.edu wrote: Hey Everyone, I just purchased Discovering CFCs by Hal Helms and I already know that the book is somewhat out of date (Hal told me so). However, what I really wanted was an introduction to OO and CFCs and this seemed like a descent starting point. I am starting to get further into the book (on page 50 right now) and I'm starting to see more CFC code. What I wanted to find out is what stuff is out of date, if it's possible to generalize. Are there any sites out there that outline the changes since MX? Any suggestions would be much appreciated! Thanks, Mike ~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;207172674;29440083;f Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:319028 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4
Re: Question about Discovering CFCs
Mike, Just this week Josh Adams gave a really good presentation on scopes. Have a watch of this I am sure it will answer many of your questions. https://admin.na3.acrobat.com/_a204547676/p74013218/ Paul. On 07/02/2009, at 10:12 PM, Mike Soultanian wrote: Brian Kotek wrote: - All function-local variables must be declared with the var keyword Yeah, I've read extensively that it's very important to do this with every variable declared inside a function. Btw, does this also mean that query names need to be var-scoped as well? i.e. cfset var GetParks = 1 cfquery name=GetParks datasource=dsn SELECT name FROM table /cfquery - The VARIABLES scope within a CFC represents private data That I understand. - The VARIABLES scope should be used instead of the THIS scope for object properties to enforce encapsulation Yeah, I noticed that the book uses the this scope. I also noticed that the book outputs data from CFCs which I've read is a nono in regards to best practices. I'm assuming the correct method to retrieve the data stored in the properties is by calling the class' methods, correct? - An init() method is the de-facto constructor method Correct me if I'm wrong, but based on my initial reading of CFCs on the web, it seems like there are three ways of setting up constructor data: putting any cf tags or functions in the constructor area, putting a cfset init() statement in the constructor area that calls the init() method, or calling the init() method during the object instantiation. Is there a preferred method? Maybe I'm not understanding the goal of the init() method and to whom that data is supposed to be made available. Is it for the purpose of providing data to the newly created object or is it to initialize data for the other methods in the class.. or both? If anyone has any pages describing constructors and their uses (even if it's in another language), that would be helpful. - We can now call super.[method] to invoke methods on a superclass. seems simple enough. Don't have any near-future plans to call super methods just yet until I get my head wrapped around this :) If you can keep those rules in your head as you read (which I realize may be difficult), the majority of the concepts are still valid (composition, polymorphism, etc,). I think knowing about the this scope best practices is helpful. Was the variables and var scope not available at the time (Yes, I know the variables scope behaves like protected, not private. Yes, I know some people prefer keeping properties in the THIS scope. I kept the list simple because it's already going to be hard enough for him to keep track of it and there's no need to dive into minutiae at this point.) I like the idea of keeping the properties local to the CFC otherwise you break the benefits of encapsulation (or at least, I see it as a benefit). What's the difference between private and protected? thanks! Mike Regards, Brian On Sat, Feb 7, 2009 at 8:06 PM, Mike Soultanian msoul...@csulb.edu wrote: Hey Everyone, I just purchased Discovering CFCs by Hal Helms and I already know that the book is somewhat out of date (Hal told me so). However, what I really wanted was an introduction to OO and CFCs and this seemed like a descent starting point. I am starting to get further into the book (on page 50 right now) and I'm starting to see more CFC code. What I wanted to find out is what stuff is out of date, if it's possible to generalize. Are there any sites out there that outline the changes since MX? Any suggestions would be much appreciated! Thanks, Mike ~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;207172674;29440083;f Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:319029 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4
Re: Question about Discovering CFCs
It's worth adding that CF8 now supports interfaces via the cfinterface tag: http://cfquickdocs.com/cf8/?getDoc=cfinterface mxAjax / CFAjax docs and other useful articles: http://www.bifrost.com.au/blog/ 2009/2/8 Brian Kotek brian...@gmail.com: Most of the general ideas are still applicable. The biggest differences that I can think of are: - All function-local variables must be declared with the var keyword - The VARIABLES scope within a CFC represents private data - The VARIABLES scope should be used instead of the THIS scope for object properties to enforce encapsulation - An init() method is the de-facto constructor method - We can now call super.[method] to invoke methods on a superclass. ~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;207172674;29440083;f Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:319030 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=11502.10531.4
Re: Question about Discovering CFCs
Correct me if I'm wrong, but based on my initial reading of CFCs on the web, it seems like there are three ways of setting up constructor data: Is there a preferred method? The difference between code at the top of your component outside any methods (which gets ran on the component's creation) and a pseduo-constructor method like init() that you call yourself upon the creation of the component is that you can pass arguments into the init method. If your only initialization is something really basic like cfset variables.instance = structnew() then the init isn't really doing anything for you. If you want to pass data into the component upon its creation to aid in its initilization or population, you will want to use init() myPerson = createobject(component,person).init(firstName=Brad,lastName=Wood); Maybe I'm not understanding the goal of the init() method and to whom that data is supposed to be made available. Is it for the purpose of providing data to the newly created object or is it to initialize data for the other methods in the class.. or both? It can be for whatever you want. :) Both of those would be fine. - We can now call super.[method] to invoke methods on a superclass. seems simple enough. Don't have any near-future plans to call super methods just yet until I get my head wrapped around this :) You won't really until you start uning inheritance and want augment functionality provided through a base class. The most often place I use super. is in my init methods. If you are extending a class with an init method, you need to make sure the child init does a super.init() or the base class's init() won't be called. What's the difference between private and protected? Private is only available to methods in that component. Protected is available to any component in the same folder. In my opinion this assumes you are using the package set up where your components are in folders like /CFC/business/person/personBean.cfc /CFC/business/person/personService.cfc /CFC/business/person/personFoo.cfc Any of those components could access each other's protected methods. Someone correct me if I am wrong, but I do not believe ColdFusion provides a way to mark a variable as protected. ~Brad ~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;207172674;29440083;f Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:319031 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4
Re: Question about Discovering CFCs
Brad, you're confusing protected with package. Package allows objects in the same package (folder) to access a variable. Protected means the variable is accessible by subclasses. On Sat, Feb 7, 2009 at 10:43 PM, Brad Wood b...@bradwood.com wrote: Private is only available to methods in that component. Protected is available to any component in the same folder. In my opinion this assumes you are using the package set up where your components are in folders like /CFC/business/person/personBean.cfc /CFC/business/person/personService.cfc /CFC/business/person/personFoo.cfc Any of those components could access each other's protected methods. Someone correct me if I am wrong, but I do not believe ColdFusion provides a way to mark a variable as protected. ~Brad ~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;207172674;29440083;f Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:319032 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=11502.10531.4
Re: Question about Discovering CFCs
On Sat, Feb 7, 2009 at 10:12 PM, Mike Soultanian msoul...@csulb.edu wrote: Yeah, I noticed that the book uses the this scope. I also noticed that the book outputs data from CFCs which I've read is a nono in regards to best practices. I'm assuming the correct method to retrieve the data stored in the properties is by calling the class' methods, correct? Right, when the book was written there was no private variables scope available within a CFC, except via a hack (which the book will show and which you can ignore). Correct me if I'm wrong, but based on my initial reading of CFCs on the web, it seems like there are three ways of setting up constructor data: putting any cf tags or functions in the constructor area, putting a cfset init() statement in the constructor area that calls the init() method, or calling the init() method during the object instantiation. Is there a preferred method? Yes, as Brad mentioned, it is the common practice to chain an init() call when you create the object. It does mean that your init() method needs to return this: cffunction name=init cfreturn this / /cffunction Maybe I'm not understanding the goal of the init() method and to whom that data is supposed to be made available. Is it for the purpose of providing data to the newly created object or is it to initialize data for the other methods in the class.. or both? If anyone has any pages describing constructors and their uses (even if it's in another language), that would be helpful. http://en.wikipedia.org/wiki/Constructor_(computer_science) A constructor in most languages is a block of code that is automatically executed when the object is created. So it is a place to set up the object and put it into a usable state. Since we don't have constructors in ColdFusion, the init() method has to be explicitly called. ~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;207172674;29440083;f Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:319033 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4
Re: Question about Discovering CFCs
What's the difference between private and protected? Private is only available to methods in that component. Protected is available to any component in the same folder. In my opinion this assumes you are using the package set up where your components are in folders like /CFC/business/person/personBean.cfc /CFC/business/person/personService.cfc /CFC/business/person/personFoo.cfc Any of those components could access each other's protected methods. Someone correct me if I am wrong, but I do not believe ColdFusion provides a way to mark a variable as protected. Someone correct me if I'm wrong too, but I don't think you can mark a function as protected. The four ACCESS attributes in CF8 are public, private, package and remote, and as Brian pointed out, you've described package. Dave Watts, CTO, Fig Leaf Software http://www.figleaf.com/ Fig Leaf Software provides the highest caliber vendor-authorized instruction at our training centers in Washington DC, Atlanta, Chicago, Baltimore, Northern Virginia, or on-site at your location. Visit http://training.figleaf.com/ for more information! ~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;207172674;29440083;f Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:319034 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=11502.10531.4
Re: Question about Discovering CFCs
Brad, you're confusing protected with package. Package allows objects in the same package (folder) to access a variable. Protected means the variable is accessible by subclasses. Oops, you're right Brian. For some reason I'm confusing the two tonight. Thanks for the correction. I've been painting tonight, so I'll blame it on the fumes :) ~Brad ~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;207172674;29440083;f Archive: http://www.houseoffusion.com/groups/cf-talk/message.cfm/messageid:319035 Subscription: http://www.houseoffusion.com/groups/cf-talk/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.4
