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object-oriented programming
with WordPress
How to approach
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Carl Alexander
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@twigpress
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carlalexander.ca
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No content
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Heard of object-oriented programming
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Tried to use it with WordPress
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Didn’t feel useful
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Common problem
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Hard to design classes that
work well with WordPress
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Why?
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Going back to the beginning
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WordPress didn't start off using
object-oriented programming
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PHP didn’t even support it well
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All procedural programming
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What is procedural programming?
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Programming using steps
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Each line of code is a step towards the
outcome that you're looking for
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It’s how you break down problems
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function get_authors_registered_after($date, $number = 5)
{
$results = array();
$authors = get_users('who=authors');
foreach ($authors as $author) {
if ($author->user_registered > $date) {
$results[] = $author;
}
if (count($results) >= $number) {
break;
}
}
return $results;
}
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function get_authors_registered_after($date, $number = 5)
{
$results = array();
$authors = get_users('who=authors');
foreach ($authors as $author) {
if ($author->user_registered > $date) {
$results[] = $author;
}
if (count($results) >= $number) {
break;
}
}
return $results;
}
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function get_authors_registered_after($date, $number = 5)
{
$results = array();
$authors = get_users('who=authors');
foreach ($authors as $author) {
if ($author->user_registered > $date) {
$results[] = $author;
}
if (count($results) >= $number) {
break;
}
}
return $results;
}
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function get_authors_registered_after($date, $number = 5)
{
$results = array();
$authors = get_users('who=authors');
foreach ($authors as $author) {
if ($author->user_registered > $date) {
$results[] = $author;
}
if (count($results) >= $number) {
break;
}
}
return $results;
}
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function get_authors_registered_after($date, $number = 5)
{
$results = array();
$authors = get_users('who=authors');
foreach ($authors as $author) {
if ($author->user_registered > $date) {
$results[] = $author;
}
if (count($results) >= $number) {
break;
}
}
return $results;
}
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function get_authors_registered_after($date, $number = 5)
{
$results = array();
$authors = get_users('who=authors');
foreach ($authors as $author) {
if ($author->user_registered > $date) {
$results[] = $author;
}
if (count($results) >= $number) {
break;
}
}
return $results;
}
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How do you convert this?
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Move everything in a class
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class Authors
{
public function get_registered_after($date, $number = 5)
{
$results = array();
$authors = get_users('who=authors');
foreach ($authors->results as $author) {
if ($author->user_registered > $date) {
$results[] = $author;
}
if (count($results) >= $number) {
break;
}
}
return $results;
}
}
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class Authors
{
public function get_registered_after($date, $number = 5)
{
$results = array();
$authors = get_users('who=authors');
foreach ($authors->results as $author) {
if ($author->user_registered > $date) {
$results[] = $author;
}
if (count($results) >= $number) {
break;
}
}
return $results;
}
}
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class Authors
{
public function get_registered_after($date, $number = 5)
{
$results = array();
$authors = get_users('who=authors');
foreach ($authors->results as $author) {
if ($author->user_registered > $date) {
$results[] = $author;
}
if (count($results) >= $number) {
break;
}
}
return $results;
}
}
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This isn't object-oriented programming
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You put your procedural code
inside a class method
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That's why using object-oriented
programming with WordPress feels bad
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Everyone tells you to
structure code that way
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Perpetuates this cycle of
misunderstanding
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Questions?
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Understanding
object-oriented programming
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Use classes working together
to solve problems
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No steps like procedural programming
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Programming using Legos (!!!)
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Classes:
Templates used to create objects
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Lego brick types
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Objects:
Individual instances of a class
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Lego bricks
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Why isn't using object-oriented
programming as easy as using Legos?
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Already have way of doing things
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Also not the complete picture
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Object-oriented programming
with WordPress
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Not just using Legos to build things
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Designing whole Lego sets
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You have to
visualize the Lego set
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You have to
design the Lego brick types
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You have to
assemble the Lego set
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A lot more than just
building something with Legos
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Most developers don't have to do this
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Object-oriented frameworks
do most of the heavy lifting for you
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They're the Lego Group
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They give you the Lego brick types
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They give you the instructions
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Original analogy works with frameworks
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Has important implications
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Similar footing with
developers using a framework
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Neither of you knows
how to think like the Lego Group
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You don't have a choice
to learn how to think that way
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Will make you a much better developer
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Questions?
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Thinking like the Lego Group
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Hard thing to do
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Strategy to start designing classes better
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Break the problem down
into smaller parts
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Think about all the Lego brick types
you might need
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What does a WordPress plugin need?
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class AdminPage
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class Options
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class Plugin
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class Metabox
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Classes representing
common WordPress elements
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Also have to think about
what’s specific to your plugin
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E-commerce plugin?
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class Product
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class Sale
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Learning management system plugin?
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class Course
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class Students
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Break your plugin or theme
into classes
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Some will be specific to WordPress
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Others to what you're building
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Add code to them next
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Properties to store data
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Methods to define behaviour
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Where things get complicated
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No right or wrong way to do it
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Don’t expect to get this all right
on the first try
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Might need to break things down
into more classes
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Might not know how to solve
a specific problem
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Might have made some
wrong assumptions
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All part of the process
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Different for everyone
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Identical outcome at the end
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Classes are no longer empty
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Start piecing these different classes
together into a Lego set
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Review
Break things down
Add code
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Repeating this cycle is the key
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Only difference is how fast you do it
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Questions?
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Thank you!