Start learning with our library of video tutorials taught by experts. Get started

WordPress: Creating Custom Widgets and Plugins with PHP

Writing a pluggable function


From:

WordPress: Creating Custom Widgets and Plugins with PHP

with Drew Falkman

Video: Writing a pluggable function

Pluggable functions are a set of functions built into WordPress. While there are many functions in WordPress, pluggable functions are special because they allow you to override them, essentially adding new functionality into the built-in workings of WordPress. All that's necessary to override pluggable functions is to create a new function with the same name. All the pluggable functions are located in wp-includes, pluggable.php file. It's a good practice often, when you are going to override a pluggable function, to start with the original pluggable function from the pluggable.php file.
Expand all | Collapse all
  1. 1m 49s
    1. Welcome
      1m 16s
    2. Using the exercise files
      33s
  2. 23m 29s
    1. WordPress overview
      2m 32s
    2. Installing WPI for Windows
      3m 42s
    3. Installing MAMP for the Mac
      3m 25s
    4. Installing and configuring WordPress
      5m 51s
    5. Comparing WordPress 3.0 with previous versions
      2m 57s
    6. Setting up a PHP/WordPress development environment
      5m 2s
  3. 14m 47s
    1. Exploring WordPress plugins
      3m 42s
    2. Administering plugins from the WordPress admin
      5m 23s
    3. Exploring where plugins reside
      2m 51s
    4. Introduction to hooks
      2m 51s
  4. 39m 28s
    1. Creating the plugin PHP file(s)
      3m 12s
    2. More on hooks: Actions and filters
      3m 15s
    3. Installation and activation
      4m 6s
    4. Writing activation code
      3m 45s
    5. Writing an action
      5m 12s
    6. Writing a filter
      4m 15s
    7. About pluggable functions
      2m 1s
    8. Writing a pluggable function
      5m 30s
    9. Using template tags
      2m 46s
    10. Introducing shortcode
      5m 26s
  5. 26m 2s
    1. Widgets and the WordPress Widgets SubPanel
      2m 54s
    2. Comparing widgets and plugins
      1m 8s
    3. Using and customizing built-in widgets
      3m 18s
    4. Creating a new widget
      7m 21s
    5. Writing the constructor and registering widgets
      5m 20s
    6. Enabling configuration of widgets
      6m 1s
  6. 44m 59s
    1. Creating an admin interface
      5m 25s
    2. Saving data to the database
      5m 39s
    3. Securing form submission with nonces
      2m 25s
    4. Options editing post-WordPress 2.7
      4m 8s
    5. Integrating with the WordPress admin menus
      3m 34s
    6. WordPress admin dashboard API
      4m 5s
    7. Using existing options and option editing pages in WordPress
      5m 19s
    8. Using jQuery and AJAX for administration
      14m 24s
  7. 27m 13s
    1. Accessing the WordPress database
      5m 45s
    2. Using the built-in schema
      2m 21s
    3. Accessing data using $wpdb
      5m 15s
    4. Creating new tables
      7m 18s
    5. Inserting data
      6m 34s
  8. 26m 27s
    1. Introducing the Loop
      6m 22s
    2. Using WP_Query()
      3m 11s
    3. Custom filtering and sticky posts
      4m 58s
    4. Using jQuery and AJAX for posts and pages
      11m 56s
  9. 12m 9s
    1. Registering and promoting plugins
      2m 28s
    2. Creating an uninstall function
      5m 53s
    3. Backward compatibility issues
      3m 48s
  10. 15m 3s
    1. Understanding security issues
      11m 20s
    2. Internationalizing your plugin
      3m 43s
  11. 18s
    1. Goodbye
      18s

Watch this entire course now—plus get access to every course in the library. Each course includes high-quality videos taught by expert instructors.

Become a member
Please wait...
WordPress: Creating Custom Widgets and Plugins with PHP
3h 51m Intermediate Nov 04, 2010

Viewers: in countries Watching now:

In WordPress: Creating Custom Widgets and Plugins with PHP, Drew Falkman teaches PHP developers how to create custom functionality for WordPress 2.0 through 3.0 using widgets and plugins. This course starts by installing and setting up WordPress 3.0 on both Mac and Windows, then provides an in-depth look at tasks related to these WordPress add-ons: installing and administering, building and customizing, creating editable options and database tables, working with posts and pages, and utilizing jQuery and AJAX. There are also tutorials dedicated to promoting a widget or plugin, adding security, and localizing the interface. Exercise files are included with the course.

Topics include:
  • Installing WPI and MAMP server solutions
  • Administering WordPress plugins
  • Introducing hooks
  • Writing the PHP for a plugin
  • Using template tags and shortcode
  • Building a new widget
  • Creating an admin interface
  • Accessing the WordPress database
  • Using jQuery and AJAX for posts and pages
  • Registering and promoting plugins
Subjects:
Developer Web CMS
Software:
WordPress
Author:
Drew Falkman

Writing a pluggable function

Pluggable functions are a set of functions built into WordPress. While there are many functions in WordPress, pluggable functions are special because they allow you to override them, essentially adding new functionality into the built-in workings of WordPress. All that's necessary to override pluggable functions is to create a new function with the same name. All the pluggable functions are located in wp-includes, pluggable.php file. It's a good practice often, when you are going to override a pluggable function, to start with the original pluggable function from the pluggable.php file.

What I am going to do is I am going to create a new plugin here called welcome.php. This is going to override the wp_new_user _notification pluggable function, which sends a message whenever a new user registers at the site. This way I can customize the message that gets send to the user, so they get the message that I want them to see. So, in the plugins directory, I've created a new file called the welcome.php. I've put in all my plugin comments, and I am ready to go. So, now I am going to go into the pluggable.php file. I am going to find that function, wp_new_user_notification.

I am going to copy this as it stands directly from the pluggable.php file, and I am going to paste it directly into my plugin file. Now that I've pasted this function into my plugin file, I simply need to override the function and change it how I want to. Most of the functionality I want to remain the same. Notice I am sending a mail to the administrator here. I don't need to change that, but I do want to change the message that's going out to the new user, which is located here.

A couple things so you don't get scared: They're using an sprintf function, which essentially allows you to replace parts of your string with the variables that you pass in-- it's simply a secure way of doing dynamic variables replacement. In addition, they have this underscore, underscore function, which we'll talk about later when we get into the internationalization. So for now, let's go ahead and create our message variable, and we are going to write some new information in here. So, I am going to use the same function that they use, in case we want to internationalize this down the road. And I am going to change this to say, 'Welcome to mmmStuff.com,' which is my blog name.

And then I am going to add some new lines, returns, and I am going to add another line. I am going to use the same methodology that they are using, which is the dot equals, and I am going to do that for the original one as well. What that does is that says, "Set this message equal to whatever is already in this variable plus whatever comes after the Equal sign," which is going to be a new part of the message, which will say, 'Here is your information for future reference.' And again, a couple of new lines, and one final line signing out, and this one will simply say, 'Feel free to come back and check on stuff often'.

So there is my new message. In order to make this function work, I simply need to activate the plugin; however, I need to be careful because in some instances, the original plugin may have already been activated because of the order of inclusion. So I need to put a special if statement that will wrap around it, and this is exactly what you'll see in the plugin.php file. I'll say not function_exists, which determines whether or not the function exists. So, if it doesn't exist, then it will go ahead and create it; otherwise it will simply ignore this piece.

So, we're going to copy our function name, paste it into here, and then make sure we close both of them. Eclipse has a special feature: if you highlight everything and hit Command+I, it'll automatically clean up your indentation. So that's an easy way to do that. So now we can save it, and we can go into our admin, and you'll see on your Plugins page your Welcome Plugin has been parsed. If we activate it, it should go through and set up that function so that the next user who registers at the web site will then be able to get your new message.

In order to enable registration at the web site, by default, WordPress has it turned off so that not everyone can register. So, we are going to go ahead and select this so that anyone can register, save the changes, and then we are going to go ahead and log out, and sign in as a new user. So, if you go to the beginning of your web site, the front page, you'll see there is a link here to register. If we click this, we'll have the option, and you can choose whatever username you want, and then enter your e-mail, and click Register.

That will then call our function, that wp_new_user_notification. Checking your e-mail. So you can see I got a welcome e-mail, Welcome to mmmStuff.com. Here is your information for future reference. It has my username and password, the URL to the web site, and then "Feel free to come back and check on stuff often." WordPress has a set of built-in functions called pluggable functions that can be overridden by plugin developers. Because these functions are called on from within WordPress and other plugins, it allows us to be able to override the default functionality, and have things work a little differently, however we may choose.

Find answers to the most frequently asked questions about WordPress: Creating Custom Widgets and Plugins with PHP.


Expand all | Collapse all
Please wait...
Q: Do I need a web hosting service for this course?
A: You don't need a hosting site to do any testing or development work that’s covered in this course. However, if you want to have your WordPress site available to the public, you will most definitely need a WordPress site. If you are hosting with an independent company, they will need to have PHP and MySQL installed, and there will be some configuration differences, but basically, you can upload anything on your local version to the web site. If you are hosting with Wordpress.com, you will need to add your plugins by uploading them manually through the WP Admin Plugin screen.
Share a link to this course
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.
Upgrade now


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.

Upgrade now

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 WordPress: Creating Custom Widgets and Plugins with PHP.

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
Welcome to the redesigned course page.

We’ve moved some things around, and now you can



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.

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