Intermediate PHP

Intermediate PHP
Bradley Holt & Matthew Weier O’Phinney

Associate values to keys

Keys can be integers (enumerative arrays) or
strings (associative arrays)

Values can be primitive types, objects, or
other arrays (multidimensional arrays)

<?php
$post = array(
'id' => 1234,
'title' => 'Intermediate PHP',
'updated' => new DateTime(
'2010-12-16T18:00:00-05:00'
),
'draft' => false,
'priority' => 0.8,
'categories' => array('PHP', 'BTV')
);

Reading, Writing, and
Appending Arrays

<?php
$post = array(
'id' => 1234,
// …
);
echo $post['title']; // Intermediate PHP

<?php
$post = array(
'id' => 1234,
// …
);
$post['title'] = 'PHP 201';

<?php
$post = array(
'id' => 1234,
'updated' => new DateTime(
'2010-12-16T18:00:00-05:00'
),
'draft' => false,
'priority' => 0.8,
);
$post['summary'] = 'Arrays, functions, and
objects';

<?php
$post = array(
// …
);
$post['categories'][] = 'Programming';
print_r($post['categories']);
/*
Array
(
[0] => PHP
[1] => BTV
[2] => Programming
)
*/

<?php
$post = array(
// …
);
$post['categories'][1] = 'Burlington';
/*
Array
(
[0] => PHP
[1] => Burlington
)
*/

<?php
$post = array(
// …
);
foreach ($post['categories'] as $v) {
echo $v . PHP_EOL;
}
/*
PHP
BTV
*/

<?php
$post = array(
// …
);
foreach ($post['categories'] as $k => $v) {
echo $k . ': ' . $v . PHP_EOL;
}
/*
0: PHP
1: BTV
*/

<?php
$post = array(
'id' => 1234,
// …
);
foreach ($post as $k => $v) {
echo $k . ': ' . $v . PHP_EOL;
}
/*
id: 1234
title: Intermediate PHP
…
*/

<?php
$post = array(
// …
);
echo implode(', ', $post['categories']);
// PHP, BTV

<?php
$post = array(
// …
'categories' =>
explode(', ', 'PHP, BTV')
);
/*
Array
(
[0] => PHP
[1] => BTV
)
*/

Array Key Exists,
In Array, and Array Keys

<?php
$post = array(
'id' => 1234,
// …
);
if (array_key_exists('categories', $post))
{
echo implode(', ', $post['categories']);
} else {
echo 'Uncategorized';
}

<?php
$post = array(
// …
);
if (in_array('PHP', $post['categories'])) {
echo 'PHP: Hypertext Preprocessor';
}

<?php
$posts = array(
1233 => array(/* … */),
1234 => array(/* … */),
);
print_r(array_keys($posts));
/*
Array
(
[0] => 1233
[1] => 1234
)
*/

<?php
$post = array(
// …
);
sort($post['categories']);
/*
Array
(
[0] => BTV
[1] => PHP
)
*/

Sorting Function
Attributes
Some sort by value, others by key

Some maintain key association, others do not

Some sort low to high, others high to low

Some are case sensitive, some are not

See:
http://www.php.net/manual/en/array.sorting.php

Sorting Functions
array_multisort() rsort()

asort() shufﬂe()

arsort() sort()

krsort() uasort()

ksort() uksort()

natcasesort() usort()

natsort()

Stacks and Queues

Photo by Phil Cooper Photo by Thomas W

Array Push and
Array Pop (stack)

<?php
$post = array(
// …
'categories' => array('PHP')
);
array_push($post['categories'], 'BTV');
echo array_pop($post['categories']);
// BTV
/*
Array
(
[0] => PHP
)
*/

Array Unshift and
Array Pop (queue)

<?php
$post = array(
// …
'categories' => array('BTV')
);
array_unshift($post['categories'], 'PHP');
/*
Array
(
[0] => PHP
[1] => BTV
)
*/
echo array_pop($post['categories']);
// BTV

<?php
print_r(get_defined_functions());
/*
Array
(
[internal] => Array
(
[0] => zend_version
[1] => func_num_args
// …
)
[user] => Array
(
)
)
*/

<?php
$functions = get_defined_functions();
echo count($functions['internal']);
// 1857

<?php
$name = 'Marcus Börger';
if (function_exists('mb_strtolower')) {
echo mb_strtolower($name, 'UTF-8');
// marcus börger
} else {
echo strtolower($name);
// marcus b?rger
}

Rules

Any valid PHP code is allowed inside
functions, including other functions and class
definitions

Function names are case-insensitive

Once defined, a function cannot be undefined

<?php
function nextId($posts)
{
return max(array_keys($posts)) + 1;
}
$posts = array(
1233 => array(/* … */),
1234 => array(/* … */),
);
echo nextId($posts); // 1235

<?php
function nextId(array $posts)
{
return max(array_keys($posts)) + 1;
}
$posts = array(
1233 => array(/* … */),
1234 => array(/* … */),
);
echo nextId(1234);
// Argument 1 passed to nextId() must be an
array, integer given

<?php
function isPublished(DateTime $published,
$draft)
{
if ($draft) { return false; }
$now = new DateTime();
return $now >= $published;
}
$published = new
DateTime('2010-12-16T18:00:00-05:00');
$draft = false;
var_dump(isPublished($published, $draft));
// bool(true)

<?php
function isPublished(DateTime $published,
$draft, $now = false)
{
if ($draft) { return false; }
$now = $now ? $now : new DateTime();
return $now >= $published;
}
$published = new
DateTime('2010-12-16T18:00:00-05:00');
$draft = false;
$now = new
DateTime('2010-12-16T17:59:59-05:00');
var_dump(isPublished($published, $draft,
$now));
// bool(false)

Function Overloading
(not really)

<?php
function nextId($arg1)
{
switch (true) {
case is_array($arg1):
return max(array_keys($arg1)) + 1;
case is_int($arg1):
return $arg1 + 1;
}
}
$posts = array(
1233 => array(/* … */),
1234 => array(/* … */),
);
echo nextId(1234); // 1235

Variable Number of
Arguments

<?php
function mostRecent()
{
$max = false;
foreach (func_get_args() as $arg) {
$max = $arg > $max ? $arg : $max;
}
return $max;
}
$mostRecent = mostRecent(
new DateTime('2010-12-14T18:00:00'),
new DateTime('2010-12-16T18:00:00'),
new DateTime('2010-12-15T18:00:00')
);
// 2010-12-16T18:00:00

Basics

Encapsulate metadata and behavior

metadata => properties (variables, constants)

behavior => methods (functions)

Cast an Associative
Array to (object)
<?php
$a = array(
'foo' => 'bar',
);
$o = (object) $a;
echo $o->foo; // 'bar'

stdClass

$o = new stdClass;
$o->foo = 'bar';
echo $o->foo; // 'bar'

Declaring a Class

<?php
class Foo
{
}

Declaring Properties

<?php
class Foo
{
protected $bar = 'bar';
}

Extending Classes

<?php
class FooBar extends Foo
{
}

Visibility
public: accessible from instances or within
methods of any visibility, and within
extending classes

protected: accessible only within instance
methods of any visibility, and within
extending classes

private: accessible only within instance
methods from the declaring class

Modiﬁers

ﬁnal: cannot be overridden in extending
classes

abstract: must be overridden in extending
classes

<?php
abstract class AbstractFoo
{
abstract public function sayBar();
}

class Foo extends AbstractFoo
{
public $bar;

public function sayBar()
{
echo $this->bar;
}
}

Interfaces
"Blueprints" for classes

Typically indicate behaviors found in
implementing classes

You can implement many interfaces, but only
extend once

Allows you to compose multiple behaviors
into a single class

<?php
interface Resource {
public function getResource();
}
interface Dispatcher {
public function dispatch();
}

abstract class DispatchableResource
implements Resource,Dispatcher
{
// …
}

<?php
interface Resource { /* … */ }
interface Dispatcher { /* … */ }

implements Resource,Dispatcher
{
protected $resource;
public function getResource() {
return $this->resource;
}
public function dispatch() {
return 'Dispatched ' . $this-
>getResource();
}
}

<?php
interface Resource { /* … */ }
interface Dispatcher { /* … */ }

implements Resource,Dispatcher { /* … */ }

class TrafficCop extends
DispatchableResource
{
protected $resource = 'traffic cop';
}
$cop = new TrafficCop();
echo $cop->dispatch();
// 'Dispatched traffic cop'

Type hinting: you can indicate an interface, abstract
class, or class name "hint" with parameters:

public function doSomething(Dispatcher
$dispatcher) {/* … */}

Test for types:

if ($object instanceof Dispatcher) { }

Type hints look at the entire inheritance chain,
including interfaces!

Statics
Static properties and methods may be
accessed without instantiation

Requires a different token to access:

ClassName::$varName for variables

Classname::methodName() for methods

or use self or parent or static within
a class, instead of the class name

Late Static Binding

static is used for "Late Static
Binding" (LSB)

<?php
class BasicPerson
{
public static $sex = 'unisex';
public static function getSex()
{
return static::$sex;
}
}
class MalePerson extends BasicPerson
{
public static $sex = 'male'; // LSB
}
echo BasicPerson::getSex(); // 'unisex'
BasicPerson::$sex = 'female';
echo BasicPerson::getSex(); // 'female'
echo MalePerson::getSex(); // 'male'

Magic Methods
Tie into different states of an object

Construct, Destruct, and
Invoke
__construct — Constructor (used when
"new Class" is called)

__destruct — Destructor (called when
object is destroyed)

__invoke — Call an object instance like a
function (echo $object();)

Sleep and Wakeup

__sleep — Deﬁne what properties should be
serialized, and how

__wakeup — Determine how to initialize state
from serialized instance

Call and Call Static

Overload method access

__call

__callStatic

Get and Set

Overload property access

__get

__set

Cardinal Rule

Objects should model discrete concepts, and
not just be a container for functions.

Thank You
Bradley Holt & Matthew Weier O’Phinney

License
Intermediate PHP is licensed under a Creative
Commons Attribution-NonCommercial-ShareAlike
3.0 Unported License.

Intermediate PHP

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