Easy-to-follow video tutorials help you learn software, creative, and business skills.Become a member

Working with LOCAL scope in functions

From: ColdFusion 9 New Features

Video: Working with LOCAL scope in functions

Dealing with variable encapsulation and objects and methods is always a lot of trouble. Making sure that you make all of your methods thread-safe by keeping their variables all tucked inside nice and neat can be laborious. And it's all too easy to miss a var keyword in front of a variable to keep it local to the function. ColdFusion 9 introduces a new scope. The LOCAL scope, that is confined to a specific method or function, making it much easier to make sure you don't accidentally leak variables outside of your functions. To demonstrate this in the Chapter4 folder, open localscope.cfm.

Working with LOCAL scope in functions

Dealing with variable encapsulation and objects and methods is always a lot of trouble. Making sure that you make all of your methods thread-safe by keeping their variables all tucked inside nice and neat can be laborious. And it's all too easy to miss a var keyword in front of a variable to keep it local to the function. ColdFusion 9 introduces a new scope. The LOCAL scope, that is confined to a specific method or function, making it much easier to make sure you don't accidentally leak variables outside of your functions. To demonstrate this in the Chapter4 folder, open localscope.cfm.

In here, I have a function written for you already that shows you all the different ways you can get variables into the LOCAL scope and when variables will not be in the LOCAL scope. So I'm just going to run through this function real quick and then we will view it in the preview and see how the dump shows where variables are getting assigned. So, in the testFunction, in these first two variable declarations you can see that the first one says cfset LOCAL.FirstName, and the second one says cfset var LastName.

The first thing you should be thinking if you have used the var keyword even once is that this is function is going to through an error because all variables with the var keyword have to be at the beginning of the function. In ColdFusion 9 that's changed. You can put a var statement on any variable that you want, anywhere in the function. And it will automatically assign that particular variable through the LOCAL scope. So, again these first two lines have either explicitly declared the LOCAL scope, or used the var keyword in order to force these variables to be inside the LOCAL scope.

Once a variable has been declared in the LOCAL scope, then if you set that value without referencing the scope, it will assume that it's in that LOCAL scope. So, in this case, these reset the values in the LOCAL scope. Even though I don't have the scope defined on the front. Now, down here where I am setting City and State, because these haven't been previously var-ed, they haven't been declared in the LOCAL scope. They are going to be put inside the global variables scope, which is available outside of the function.

So, let's take a look at this in our preview and see exactly what happens. In Safari, I can see my LOCAL scope dump inside of the function and you can see that LOCAL also includes arguments. So if I do LOCAL.arguments. testargument, I would get Dan. The same as if I just did arguments.testargument. Here we can see Terrence and Ryan as the FIRSTNAME and LASTNAME and inside our LOCAL scope. Then I have just dumped the variable scope inside the function and the variable scope outside the function.

And I have limited them to just to show these specific keys so we don't have a whole bunch of garbage to display. So, if I go back to my source code, and change the City and State to have the var in front of them, you can now see that they have been moved into the LOCAL s cope, and are not available outside the function. My other option is to just to prefix them with LOCAL. So, I will do that for both City and State, preview the file again, and you can see it has the exact same effect.

The City and the State are now inside of the LOCAL scope. If you're like me, you've made a habit of defining a local structure in order to keep your variables inside the function. So almost all of my methods and functions start like this. I've always created a LOCAL scope in order to be able to just use variables willy-nilly without having to worry about always varing every single thing. So, if I go and save this and preview again, it has no effect whatsoever on the actual functionality of the page.

ColdFusion is smart enough to know that I'm just really carrying a LOCAL scope and it will ignore that statement. So that's all there is to the LOCAL scope. You still need to make sure that you var all of your variables if you're not going to use the explicit LOCAL scope notation. If you are like me and you have already made a habit of creating a LOCAL scope in your functions and methods, this is going to really change from the way you have always worked. The biggest takeaway is that you can now var your variables anyplace you want. And in fact with the new chained operators that I talked about in an earlier video, you can even var all of your variables in one fell swoop.

So for example, I can, cfset var Firstname = Lastname = empty string. And I can var all my variables in one shot.

Show transcript

This video is part of

Image for ColdFusion 9 New Features
ColdFusion 9 New Features

36 video lessons · 2908 viewers

Daniel Short
Author

 
Expand all | Collapse all
  1. 4m 30s
    1. Welcome
      53s
    2. Using the exercise files
      3m 37s
  2. 7m 48s
    1. Adding managing and comparing servers
      5m 26s
    2. Monitoring server health
      2m 22s
  3. 22m 10s
    1. Setting the default data source and SMTP
      5m 6s
    2. Getting programmatic debugging and exception handling
      5m 54s
    3. Reviewing the new onCFCRequest method
      5m 29s
    4. Using ApplicationStop()
      2m 24s
    5. Working with Server.cfc and onServerStart
      3m 17s
  4. 17m 45s
    1. Using ternary and chained operations
      5m 46s
    2. Using New and Import
      4m 2s
    3. Reviewing CFScript enhancements
      7m 57s
  5. 20m 23s
    1. Building with implicit getters and setters
      4m 26s
    2. Working with LOCAL scope in functions
      4m 35s
    3. Serializing objects
      6m 6s
    4. Writing components in CFScript
      5m 16s
  6. 19m 27s
    1. Getting started with ORM
      5m 51s
    2. Logging ORM activity
      2m 13s
    3. Saving objects to the database
      6m 10s
    4. Defining table relationships
      5m 13s
  7. 16m 59s
    1. Caching page fragments
      5m 29s
    2. Managing the cache
      4m 48s
    3. Working with in-memory files using VFS (RAM disks)
      6m 42s
  8. 12m 39s
    1. Working with Excel spreadsheets
      4m 56s
    2. Working with Word documents
      4m 4s
    3. Working with PowerPoint presentations
      3m 39s
  9. 28m 58s
    1. Loading Google maps with markers onto a page
      4m 53s
    2. Adding a Flash movie with the built-in FLV player
      2m 14s
    3. Using multi-file upload control
      6m 7s
    4. Building a progress indicator
      3m 37s
    5. Working with accordion layouts
      3m 18s
    6. Showing information with data grid enhancements
      5m 1s
    7. Informing users with Confirm Alert and Prompt dialog boxes
      3m 48s
  10. 9m 8s
    1. Accessing IMAP accounts
      6m 31s
    2. Working with the new array functions
      2m 37s
  11. 15s
    1. Goodbye
      15s

Start learning today

Get unlimited access to all courses for just $25/month.

Become a member
Sometimes @lynda teaches me how to use a program and sometimes Lynda.com changes my life forever. @JosefShutter
@lynda lynda.com is an absolute life saver when it comes to learning todays software. Definitely recommend it! #higherlearning @Michael_Caraway
@lynda The best thing online! Your database of courses is great! To the mark and very helpful. Thanks! @ru22more
Got to create something yesterday I never thought I could do. #thanks @lynda @Ngventurella
I really do love @lynda as a learning platform. Never stop learning and developing, it’s probably our greatest gift as a species! @soundslikedavid
@lynda just subscribed to lynda.com all I can say its brilliant join now trust me @ButchSamurai
@lynda is an awesome resource. The membership is priceless if you take advantage of it. @diabetic_techie
One of the best decision I made this year. Buy a 1yr subscription to @lynda @cybercaptive
guys lynda.com (@lynda) is the best. So far I’ve learned Java, principles of OO programming, and now learning about MS project @lucasmitchell
Signed back up to @lynda dot com. I’ve missed it!! Proper geeking out right now! #timetolearn #geek @JayGodbold
Share a link to this course

What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

Become a member Download sample files See plans and pricing

Please wait... please wait ...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

Join now "Already a member? Log in

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed ColdFusion 9 New Features.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Are you sure you want to delete this note?

No

Your file was successfully uploaded.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.