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

Using "finally" with "try" and "catch"

From: PHP 5.5 First Look

Video: Using "finally" with "try" and "catch"

One of the cooler features of object-oriented PHP is exceptions. An exception is a response to an abnormal event that typically requires the changing of the normal program execution flow. Up to this point, PHP has allowed code to try or attempt to do something. If an exception is thrown or created it can be caught, meaning handled gracefully. However, some program flows require some kind of closing operation that needs to happen even if there is an exceptional situation. Here's an example of pseudo code before PHP 5.5.

Using "finally" with "try" and "catch"

One of the cooler features of object-oriented PHP is exceptions. An exception is a response to an abnormal event that typically requires the changing of the normal program execution flow. Up to this point, PHP has allowed code to try or attempt to do something. If an exception is thrown or created it can be caught, meaning handled gracefully. However, some program flows require some kind of closing operation that needs to happen even if there is an exceptional situation. Here's an example of pseudo code before PHP 5.5.

I'm going to lock database tables, attempt to write to the database, and then unlock the tables. If there's a problem, report the problem and unlock the tables. Notice that I have to manually unlock the tables in both steps. In PHP a new block is now available called Finally. Finally executes after a try/catch block and before normal execution resumes, which allows cleanup operation to run even if there's a problem. Here's how the same functionality would look in PHP 5.5, with less redundant code.

going to lock tables. Then try writing to the database. If there's a problem, I'll catch it. And finally, no matter what, I'll unlock the tables at the end. Let's see this in action. In NetBeans I'm navigate to pages > generate.inc.php. This is a page that will generate a 100 fictitious log entries of a non existent game. It starts off with a database connection which I put into exception mode. Then I lock the tables. So far, so good.

I start a try block, where I begin a transaction, prepare a statement, then loop through it 100 times. At the end of the loop, I commit, then unlock the tables. That's a lot of work in a single try block. After the try, There's a catch where if there's a problem I roll back the transaction, report that there was a problem and unlock the tables. To see this in action, let's go to the browser. Click on Generate. I'll see some Success and Info messages.

I'm going to look into the database to see the generated entries. Local host port 8080 and I'm going to go to PHP.myadmin, then I go to Sandbox and the log table. There's 100 total. Since these are random your rows may look a little different but you get the point. I'm going to switch back to the code and clean it up to make it more elegant. I'm going to add a finally block after the catch using the finally keyword. Finally. Either I'm going to unlock the tables.

So, unlock the tables. Database. Pdo. Exec. Unlock tables. And I'll show the success message there. I'm going to remove the unlocking from both the catch and the try, and save. I'm going to rerun the code in the browser, by clicking on generate again. Now when I got back to the table. And I can see that more entries were generated.

Going back to the application, click on log. This is going to render the log, for game one, with no security. Let's add a password to this process to only show the game log to somebody who has access.

Show transcript

This video is part of

Image for PHP 5.5 First Look
PHP 5.5 First Look

14 video lessons · 3654 viewers

Jon Peck
Author

 

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.

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 PHP 5.5 First Look.

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.