PHP 5.5 First Look
Illustration by Don Barnett

Combining foreach() with list()


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PHP 5.5 First Look

with Jon Peck

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Video: Combining foreach() with list()

As a developer, one of the common tasks that I see on a regular basis is looping over a result set. Depending on the circumstances, I may need to assign a group of variables to property values or values in an array. Up to this point it's been a manual process, but in PHP 5.5, it's now possible to combine for each with List. This allows me to iterate over the array and unpack nested arrays into looped variables. Using the language construct list as a variable. There is a limitation, I can't use list as a key element, which makes sense.
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Watch the Online Video Course PHP 5.5 First Look
42m 29s Intermediate Jun 14, 2013

Viewers: in countries Watching now:

Join author Jon Peck as he demonstrates new functionality in PHP 5.5, including generators, the try-catch-finally execution model, and a brand-new password hashing API. A number of existing behaviors, such as the foreach() and empty() functions, have also been updated, and Jon explores what changed and how it can be used. Throughout this course, you'll learn to add new functionality to a simple deck of cards class using these new and updated features, and how to use them for the basis of your own project.

Topics include:
  • Using generators to create simple iterators
  • Dereferencing strings and arrays
  • Enhancing security with the password hashing API
  • Replacing APC with OPcache
  • Normalizing Boolean and unpack() behavior
  • Surveying the removed, incompatible, and deprecated functionality
Subject:
Developer
Software:
PHP
Author:
Jon Peck

Combining foreach() with list()

As a developer, one of the common tasks that I see on a regular basis is looping over a result set. Depending on the circumstances, I may need to assign a group of variables to property values or values in an array. Up to this point it's been a manual process, but in PHP 5.5, it's now possible to combine for each with List. This allows me to iterate over the array and unpack nested arrays into looped variables. Using the language construct list as a variable. There is a limitation, I can't use list as a key element, which makes sense.

How am I going to get multiple keys? This sounds neat, in theory, so let's see it in action. If we look at the log, we can see it's pretty straight forward. And it's rendering some kind of log entry that's stored in the database. Let's see what that code looks like. I'm going to go back to the IDE. Then navigate to Classes>Log.php. Take a look at the method toHtml. There's a 4H Loop that goes through each row and sends variables to a method that parses them cleanly.

Row zero, row one, row two, row three. Now, this is perfectly functional code, but talk about ovsication. I could tell the database query to return an associative array, which would make it easier to read, but it's still longer. Let's try something more elegant using the combination of 4H end list. I'll start with only one variable. For each this rows as list player name. Then, as the return value, let's return ret val li and then the player name.

And close the li. Save, then go back to the browser and refresh the page. Now, I'm only seeing the player identifiers but no errors. Good so far. Let's populate the rest of it. Going back to the IDE, assign logical variable names to the list, so player name followed by the action, the card, underscore text, and the target player name. Then, I'll modify the original snippet and pass two string, the player name, the action, card text, and target player name, save, and go back to the browser and refresh. This time, the entire human readable log entry is shown. Something to keep in mind: this technique will cause a problem if you have too many variables and not enough data.

Back to Log, I'm going to intentionally add one additional variable called Too Many. Save, then Refresh. As there's not enough elements, a notice will be thrown for the undefined offset. I'm going to fix the log now and remove that, and Save. To review, PHP 5.5 now allows me to combine 4H with List to populate variables from an array or an object that can be iterated like an array.

Find answers to the most frequently asked questions about PHP 5.5 First Look .


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Q: How do I import the php55.sql file into MySQL?
A: Copy the php55.sql file from the Exercise Files folder to somewhere you can access it at the command line. (In this course, that's the 'sandbox' folder.)
 
Then type:
mysql -user=sandbox -password=sandbox sandbox < php55.sql
 
Be sure to substitute your MySQL username and password if necessary.
 
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